Method and device for occupying resources in nr v2x

ABSTRACT

Provided are a method for transmitting sidelink information by means of a first device ( 100 ) and a device for supporting same in a wireless communication system. The method may comprise the steps of: determining a plurality of candidate resources on the basis of a threshold; selecting, from the plurality of candidate resources and in a specific time interval, a resource for transmitting sidelink information; and transmitting the sidelink information on the resource.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

The present disclosure is related to a wireless communication system.

Related Art

A wireless communication system is a multiple access system thatsupports communication of multiple users by sharing available systemresources (e.g., a bandwidth, transmission power, and so on) among them.Examples of multiple access systems include a Code Division MultipleAccess (CDMA) system, a Frequency Division Multiple Access (FDMA)system, a Time Division Multiple Access (TDMA) system, an OrthogonalFrequency Division Multiple Access (OFDMA) system, a Single CarrierFrequency Division Multiple Access (SC-FDMA) system, and a Multi-CarrierFrequency Division Multiple Access (MC-FDMA) system.

FIG. 1 shows examples of 5G usage scenarios to which the technicalfeatures of the present disclosure can be applied. The 5G usagescenarios shown in FIG. 1 are only exemplary, and the technical featuresof the present disclosure can be applied to other 5G usage scenarioswhich are not shown in FIG. 1.

Referring to FIG. 1, the three main requirement areas of 5G include (1)enhanced mobile broadband (eMBB) domain, (2) massive machine typecommunication (mMTC) area, and (3) ultra-reliable and low latencycommunications (URLLC) area. Some usage cases may require multiple areasfor optimization and, other usage cases may only focus on only one keyperformance indicator (KPI). 5G is to support these various usage casesin a flexible and reliable way.

eMBB focuses on across-the-board enhancements to the data rate, latency,user density, capacity and coverage of mobile broadband access. The eMBBaims approximately 10 Gbps of throughput. eMBB far surpasses basicmobile Internet access and covers rich interactive work and media andentertainment applications in cloud and/or augmented reality. Data isone of the key drivers of 5G and may not be able to see dedicated voiceservices for the first time in the 5G era. In 5G, the voice is expectedto be processed as an application simply using the data connectionprovided by the communication system. The main reason for the increasedvolume of traffic is an increase in the size of the content and anincrease in the number of applications requiring high data rates.Streaming services (audio and video), interactive video and mobileInternet connectivity will become more common as more devices connect tothe Internet. Many of these applications require always-on connectivityto push real-time information and notifications to the user. Cloudstorage and applications are growing rapidly in mobile communicationplatforms, which can be applied to both work and entertainment. Cloudstorage is a special usage case that drives growth of uplink data rate.5G is also used for remote tasks on the cloud and requires much lowerend-to-end delay to maintain a good user experience when the tactileinterface is used. In entertainment, for example, cloud games and videostreaming are another key factor that increases the demand for mobilebroadband capabilities. Entertainment is essential in smartphones andtablets anywhere, including high mobility environments such as trains,cars and airplanes. Another usage case is augmented reality andinformation retrieval for entertainment. Here, augmented realityrequires very low latency and instantaneous data amount.

mMTC is designed to enable communication between devices that arelow-cost, massive in number and battery-driven, intended to supportapplications, such as smart metering, logistics, and field and bodysensors. mMTC aims approximately 10 years on battery and/orapproximately 1 million devices/km². mMTC allows seamless integration ofembedded sensors in all areas and is one of the most widely used 5Gapplications. Potentially by 2020, IoT devices are expected to reach20.4 billion. Industrial IoT is one of the areas where 5G plays a keyrole in enabling smart cities, asset tracking, smart utilities,agriculture and security infrastructures.

URLLC will make it possible for devices and machines to communicate withultra-reliability, very low latency and high availability, making itideal for vehicular communication, industrial control, factoryautomation, remote surgery, smart grids and public safety applications.URLLC aims approximately lms of latency. URLLC includes new servicesthat will change the industry through links with ultra-reliability/lowlatency, such as remote control of key infrastructure and self-drivingvehicles. The level of reliability and latency is essential for smartgrid control, industrial automation, robotics, drone control andcoordination.

Next, a plurality of usage cases included in the triangle of FIG. 1 willbe described in more detail.

5G can complement fiber-to-the-home (FTTH) and cable-based broadband (orDOCSIS) as a means of delivering streams rated from hundreds of megabitsper second to gigabits per second. This high speed can be required todeliver TVs with resolutions of 4K or more (6K, 8K and above) as well asvirtual reality (VR) and augmented reality (AR). VR and AR applicationsinclude mostly immersive sporting events. Certain applications mayrequire special network settings. For example, in the case of a VR game,a game company may need to integrate a core server with an edge networkserver of a network operator to minimize delay.

Automotive is expected to become an important new driver for 5G, withmany usage cases for mobile communications to vehicles. For example,entertainment for passengers demands high capacity and high mobilebroadband at the same time. This is because future users will continueto expect high-quality connections regardless of their location andspeed. Another usage case in the automotive sector is an augmentedreality dashboard. The driver can identify an object in the dark on topof what is being viewed through the front window through the augmentedreality dashboard. The augmented reality dashboard displays informationthat will inform the driver about the object's distance and movement. Inthe future, the wireless module enables communication between vehicles,information exchange between the vehicle and the supportinginfrastructure, and information exchange between the vehicle and otherconnected devices (e.g., devices accompanied by a pedestrian). Thesafety system allows the driver to guide the alternative course ofaction so that he can drive more safely, thereby reducing the risk ofaccidents. The next step will be a remotely controlled vehicle orself-driving vehicle. This requires a very reliable and very fastcommunication between different self-driving vehicles and betweenvehicles and infrastructure. In the future, a self-driving vehicle willperform all driving activities, and the driver will focus only ontraffic that the vehicle itself cannot identify. The technicalrequirements of self-driving vehicles require ultra-low latency andhigh-speed reliability to increase traffic safety to a level notachievable by humans.

Smart cities and smart homes, which are referred to as smart societies,will be embedded in high density wireless sensor networks. Thedistributed network of intelligent sensors will identify conditions forcost and energy-efficient maintenance of a city or house. A similarsetting can be performed for each home. Temperature sensors, windows andheating controllers, burglar alarms and appliances are all wirelesslyconnected. Many of these sensors typically require low data rate, lowpower and low cost. However, for example, real-time HD video may berequired for certain types of devices for monitoring.

The consumption and distribution of energy, including heat or gas, ishighly dispersed, requiring automated control of distributed sensornetworks. The smart grid interconnects these sensors using digitalinformation and communication technologies to collect and act oninformation. This information can include supplier and consumerbehavior, allowing the smart grid to improve the distribution of fuel,such as electricity, in terms of efficiency, reliability, economy,production sustainability, and automated methods. The smart grid can beviewed as another sensor network with low latency.

The health sector has many applications that can benefit from mobilecommunications. Communication systems can support telemedicine toprovide clinical care in remote locations. This can help to reducebarriers to distance and improve access to health services that are notcontinuously available in distant rural areas. It is also used to savelives in critical care and emergency situations. Mobile communicationbased wireless sensor networks can provide remote monitoring and sensorsfor parameters, such as heart rate and blood pressure.

Wireless and mobile communications are becoming increasingly importantin industrial applications. Wiring costs are high for installation andmaintenance. Thus, the possibility of replacing a cable with a wirelesslink that can be reconfigured is an attractive opportunity in manyindustries. However, achieving this requires that wireless connectionsoperate with similar delay, reliability, and capacity as cables and thattheir management is simplified. Low latency and very low errorprobabilities are new requirements that need to be connected to 5G.

Logistics and freight tracking are important usage cases of mobilecommunications that enable tracking of inventory and packages anywhereusing location-based information systems. Usage cases of logistics andfreight tracking typically require low data rates, but require a largerange and reliable location information.

Sidelink (SL) communication is a communication scheme in which a directlink is established between User Equipments (UEs) and the UEs exchangevoice and data directly with each other without intervention of anevolved Node B (eNB). SL communication is under consideration as asolution to the overhead of eNB caused by rapidly increasing datatraffic.

Vehicle-to-everything (V2X) refers to a communication technology throughwhich a vehicle exchanges information with another vehicle, apedestrian, an object having an infrastructure (or infra) establishedtherein, and so on. The V2X may be divided into 4 types, such asvehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I),vehicle-to-network (V2N), and vehicle-to-pedestrian (V2P). The V2Xcommunication may be provided via a PC5 interface and/or Uu interface.

Meanwhile, as a wider range of communication devices require largercommunication capacities, the need for mobile broadband communicationthat is more enhanced than the existing Radio Access Technology (RAT) isrising. Accordingly, discussions are made on services and user equipment(UE) that are sensitive to reliability and latency. And, a nextgeneration radio access technology that is based on the enhanced mobilebroadband communication, massive MTC, Ultra-Reliable and Low LatencyCommunication (URLLC), and so on, may be referred to as a new radioaccess technology (RAT) or new radio (NR). Herein, the NR may alsosupport vehicle-to-everything (V2X) communication.

SUMMARY OF THE DISCLOSURE

Meanwhile, when traffic increases rapidly in NR sidelink or NR V2X, a UEneeds to effectively occupy a resource. Therefore, there is a need topropose a method in which the UE effectively occupies the resource, andan apparatus supporting the method.

In an embodiment, there is provided a method of transmitting sidelinkinformation by a first apparatus 100 in a wireless communication system.The method may include: determining a plurality of candidate resources,based on a threshold; selecting a resource for transmitting the sidelinkinformation in a specific time duration, from among the plurality ofcandidate resources; and transmitting the sidelink information on theresource.

In another embodiment, there is provided a first apparatus 100 fortransmitting sidelink information in a wireless communication system.The first apparatus 100 may include: one or more memories 104; one ormore transceivers 106; and one or more processors 102 coupling the oneor more memories 104 and the one or more transceivers 106. The one ormore processors 102 may be configured to control: determining aplurality of candidate resources, based on a threshold; selecting aresource for transmitting the sidelink information in a specific timeduration, from among the plurality of candidate resources; andtransmitting the sidelink information on the resource by the one or moretransceiver 106.

EFFECTS OF THE DISCLOSURE

In sidelink communication, a user equipment (UE) can efficiently occupyresources.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows examples of 5G usage scenarios to which the technicalfeatures of the present disclosure can be applied.

FIG. 2 shows a structure of an LTE system to which an exemplaryembodiment of the present disclosure can be applied.

FIG. 3 shows a radio protocol architecture of a user plane to which anexemplary embodiment of the present disclosure can be applied.

FIG. 4 shows a radio protocol architecture of a control plane to whichan exemplary embodiment of the present disclosure can be applied.

FIG. 5 shows a structure of an NR system to which an exemplaryembodiment of the present disclosure can be applied.

FIG. 6 shows a functional division between an NG-RAN and a 5GC to whichan exemplary embodiment of the present disclosure can be applied.

FIG. 7 shows a structure of a radio frame of an NR to which an exemplaryembodiment of the present disclosure can be applied.

FIG. 8 shows a structure of a slot of an NR frame to which an exemplaryembodiment of the present disclosure can be applied.

FIG. 9 shows a protocol stack for a sidelink communication to which theexemplary embodiment of the present disclosure can be applied.

FIG. 10 shows a protocol stack for a sidelink communication to which theexemplary embodiment of the present disclosure can be applied.

FIG. 11 shows a UE performing V2X or sidelink communication to which anexemplary embodiment of the present disclosure can be applied.

FIG. 12 shows an exemplary configuration of a resource unit to which anexemplary embodiment of the present disclosure can be applied.

FIG. 13 shows user equipment (UE) operations according to a transmissionmode (TM) being related to sidelink/V2X communication to which anexemplary embodiment of the present disclosure can be applied.

FIG. 14 shows an example of a resource selection method of a UEaccording to a mode 4 of LTE V2X communication to which an embodiment ofthe present disclosure is applicable.

FIG. 15 shows a resource selection method of a UE according to anembodiment of the present disclosure.

FIG. 16 shows a specific example of resource selection according to thepresent disclosure.

FIG. 17 shows another example of extracting a threshold of the UEaccording to the present disclosure.

FIG. 18 shows a procedure of limiting resource occupancy of atransmitting UE, according to an embodiment of the present disclosure.

FIG. 19 is a drawing for explaining a problem which may occur when atransmitting UE selects a transmission resource from among occupiableresources.

FIG. 20 shows an example of selecting a transmission resource from amongresources that can be occupied by a transmitting UE, according to anembodiment of the present disclosure.

FIG. 21 shows an example of selecting a transmission resource from amongresources that can be occupied by a plurality of transmitting UEs,according to an embodiment of the present disclosure.

FIG. 22 shows a method of transmitting sidelink information by a firstapparatus 100 according to an embodiment of the present disclosure.

FIG. 23 shows a communication system (1) applied to the presentdisclosure.

FIG. 24 shows wireless devices applicable to the present disclosure.

FIG. 25 shows a signal process circuit for a transmission signal.

FIG. 26 shows another example of a wireless device applied to thepresent disclosure.

FIG. 27 shows a hand-held device applied to the present disclosure.

FIG. 28 shows a vehicle or an autonomous driving vehicle applied to thepresent disclosure.

FIG. 29 shows a vehicle applied to the present disclosure.

FIG. 30 shows an XR device applied to the present disclosure.

FIG. 31 shows a robot applied to the present disclosure.

FIG. 32 shows an AI device applied to the present disclosure.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

In this document, the term “/” and “,” should be interpreted to indicate“and/or”. For instance, the expression “A/B” may mean “A and/or B”.Further, “A, B” may mean “A and/or B”. Further, “A/B/C” may mean “atleast one of A, B, and/or C”. Also, “A, B, C” may mean “at least one ofA, B, and/or C”.

Further, in the document, the term “or” should be interpreted toindicate “and/or”. For instance, the expression “A or B” may comprise 1)only A, 2) only B, and/or 3) both A and B. In other words, the term “or”in this document should be interpreted to indicate “additionally oralternatively”.

The technology described below may be used in various wirelesscommunication systems such as code division multiple access (CDMA),frequency division multiple access (FDMA), time division multiple access(TDMA), orthogonal frequency division multiple access (OFDMA), singlecarrier frequency division multiple access (SC-FDMA), and so on. TheCDMA may be implemented with a radio technology, such as universalterrestrial radio access (UTRA) or CDMA-2000. The TDMA may beimplemented with a radio technology, such as global system for mobilecommunications (GSM)/general packet ratio service (GPRS)/enhanced datarate for GSM evolution (EDGE). The OFDMA may be implemented with a radiotechnology, such as institute of electrical and electronics engineers(IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, evolved UTRA(E-UTRA), and so on. IEEE 802.16m is an evolved version of IEEE 802.16eand provides backward compatibility with a system based on the IEEE802.16e. The UTRA is part of a universal mobile telecommunication system(UMTS). 3rd generation partnership project (3GPP) long term evolution(LTE) is part of an evolved UMTS (E-UMTS) using the E-UTRA. The 3GPP LTEuses the OFDMA in a downlink and uses the SC-FDMA in an uplink.LTE-advanced (LTE-A) is an evolution of the LTE.

5G NR is a successive technology of LTE-A, which is a new Clean-slatetype mobile communication system having the characteristics of highperformance, low latency, high availability, and so on. 5G NR may useresources of all spectrum available for usage including low frequencybands of less than 1GHz, middle frequency bands ranging from 1 GHz to 10GHz, high frequency (millimeter waves) of 24 GHz or more, and so on.

For clarity in the description, the following description will mostlyfocus on LTE-A or 5G NR. However, technical features of the presentdisclosure will not be limited only to this.

FIG. 2 shows a structure of an LTE system to which an exemplaryembodiment of the present disclosure can be applied. This may also bereferred to as an Evolved-UMTS Terrestrial Radio Access Network(E-UTRAN), or a Long Term Evolution (LTE)/LTE-A system.

Referring to FIG. 2, the E-UTRAN includes a base station (BS) (20),which provides a control plane and a user plane to a user equipment (UE)(10). The UE (10) may be fixed or mobile and may also be referred to byusing different terms, such as Mobile Station (MS), User Terminal (UT),Subscriber Station (SS), Mobile Terminal (MT), wireless device, and soon. The base station (20) refers to a fixed station that communicatedwith the UE (10) and may also be referred to by using different terms,such as evolved-NodeB (eNB), Base Transceiver System (BTS), Access Point(AP), and so on.

The base stations (20) are interconnected to one another through an X2interface. The base stations (20) are connected to an Evolved PacketCore (EPC) (30) through an 51 interface. More specifically, the basestations (20) are connected to a Mobility Management Entity (MME)through an S1-MME interface and connected to Serving Gateway (S-GW)through an S1-U interface.

The EPC (30) is configured of an MME, an S-GW, and a Packet DataNetwork-Gateway (P-GW). The MME has UE access information or UEcapability information, and such information may be primarily used in UEmobility management. The S-GW is a gateway having an E-UTRAN as itsendpoint. And, the P-GW is a gateway having a PDN as its endpoint.

Layers of a radio interface protocol between the UE and the network maybe classified into a first layer (L1), a second layer (L2), and a thirdlayer (L3) based on the lower three layers of an open systeminterconnection (OSI) model, which is well-known in the communicationsystem. Herein, a physical layer belonging to the first layer provides aphysical channel using an Information Transfer Service, and a RadioResource Control (RRC) layer, which is located in the third layer,executes a function of controlling radio resources between the UE andthe network. For this, the RRC layer exchanges RRC messages between theUE and the base station.

FIG. 3 shows a radio protocol architecture of a user plane to which anexemplary embodiment of the present disclosure can be applied. FIG. 4shows a radio protocol architecture of a control plane to which anexemplary embodiment of the present disclosure can be applied. The userplane is a protocol stack for user data transmission, and the controlplane is a protocol stack for control signal transmission.

Referring to FIG. 3 and FIG. 4, a physical (PHY) layer belongs to theL1. A physical (PHY) layer provides an information transfer service to ahigh layer through a physical channel. The PHY layer is connected to amedium access control (MAC) layer. Data is transferred (or transported)between the MAC layer and the PHY layer through a transport channel. Thetransport channel is sorted (or categorized) depending upon how andaccording to which characteristics data is being transferred through theradio interface.

Between different PHY layers, i.e., a PHY layer of a transmitter and aPHY layer of a receiver, data is transferred through the physicalchannel. The physical channel may be modulated by using an orthogonalfrequency division multiplexing (OFDM) scheme and uses time andfrequency as radio resource.

The MAC layer provides services to a radio link control (RLC) layer,which is a high layer of the MAC layer, via a logical channel. The MAClayer provides a function of mapping multiple logical channels tomultiple transport channels. The MAC layer also provides a function oflogical channel multiplexing by mapping multiple logical channels to asingle transport channel. The MAC layer provides data transfer servicesover logical channels.

The RLC layer performs concatenation, segmentation, and reassembly ofRLC SDU. In order to ensure various quality of service (QoS) required bya radio bearer (RB), the RLC layer provides three types of operationmodes, i.e., a transparent mode (TM), an unacknowledged mode (UM), andan acknowledged mode (AM). An AM RLC provides error correction throughan automatic repeat request (ARQ).

The radio resource control (RRC) layer is defined only in a controlplane. And, the RRC layer performs a function of controlling logicalchannel, transport channels, and physical channels in relation withconfiguration, re-configuration, and release of radio bearers. The RBrefers to a logical path being provided by the first layer (PHY layer)and the second layer (MAC layer, RLC layer, PDCP layer) in order totransport data between the UE and the network.

Functions of a Packet Data Convergence Protocol (PDCP) in the user planeinclude transfer, header compression, and ciphering of user data.Functions of a Packet Data Convergence Protocol (PDCP) in the controlplane include transfer and ciphering/integrity protection of controlplane data.

The configuration of the RB refers to a process for specifying a radioprotocol layer and channel properties in order to provide a particularservice and for determining respective detailed parameters and operationmethods. The RB may then be classified into two types, i.e., a signalingradio bearer (SRB) and a data radio bearer (DRB). The SRB is used as apath for transmitting an RRC message in the control plane, and the DRBis used as a path for transmitting user data in the user plane.

When an RRC connection is established between an RRC layer of the UE andan RRC layer of the E-UTRAN, the UE is in an RRC_CONNECTED state, and,otherwise, the UE may be in an RRC_IDLE state. In case of the NR, anRRC_INACTIVE state is additionally defined, and a UE being in theRRC_INACTIVE state may maintain its connection with a core networkwhereas its connection with the base station is released.

Downlink transport channels transmitting (or transporting) data from anetwork to a UE include a Broadcast Channel (BCH) transmitting systeminformation and a downlink Shared Channel (SCH) transmitting other usertraffic or control messages. Traffic or control messages of downlinkmulticast or broadcast services may be transmitted via the downlink SCHor may be transmitted via a separate downlink Multicast Channel (MCH).Meanwhile, uplink transport channels transmitting (or transporting) datafrom a UE to a network include a Random Access Channel (RACH)transmitting initial control messages and an uplink Shared Channel (SCH)transmitting other user traffic or control messages.

Logical channels existing at a higher level than the transmissionchannel and being mapped to the transmission channel may include aBroadcast Control Channel (BCCH), a Paging Control Channel (PCCH), aCommon Control Channel (CCCH), a Multicast Control Channel (MCCH), aMulticast Traffic Channel (MTCH), and so on.

A physical channel is configured of a plurality of OFDM symbols in thetime domain and a plurality of subcarriers in the frequency domain. Onesubframe is configured of a plurality of OFDM symbols in the timedomain. A resource block is configured of a plurality of OFDM symbolsand a plurality of subcarriers in resource allocation units.Additionally, each subframe may use specific subcarriers of specificOFDM symbols (e.g., first OFDM symbol) of the corresponding subframe fora Physical Downlink Control Channel (PDCCH), i.e., L1/L2 controlchannels. A Transmission Time Interval (TTI) refers to a unit time of asubframe transmission.

FIG. 5 shows a structure of an NR system to which an exemplaryembodiment of the present disclosure can be applied.

Referring to FIG. 5, an NG-RAN may include a gNB and/or eNB providing auser plane and control plane protocol termination to a user. FIG. 4shows a case where the NG-RAN includes only the gNB. The gNB and the eNBare connected to one another via Xn interface. The gNB and the eNB areconnected to one another via 5th Generation (5G) Core Network (5GC) andNG interface. More specifically, the gNB and the eNB are connected to anaccess and mobility management function (AMF) via NG-C interface, andthe gNB and the eNB are connected to a user plane function (UPF) viaNG-U interface.

FIG. 6 shows a functional division between an NG-RAN and a 5GC to whichan exemplary embodiment of the present disclosure can be applied.

Referring to FIG. 6, the gNB may provide functions, such as Inter CellRadio Resource Management (RRM), Radio Bearer (RB) control, ConnectionMobility Control, Radio Admission Control, Measurement Configuration &Provision, Dynamic Resource Allocation, and so on. An AMF may providefunctions, such as NAS security, Idle state mobility processing, and soon. A UPF may provide functions, such as Mobility Anchoring, PDUprocessing, and so on. A Session Management Function (SMF) may providefunctions, such as user equipment (UE) IP address allocation, PDUsession control, and so on.

FIG. 7 shows a structure of a radio frame of an NR to which an exemplaryembodiment of the present disclosure can be applied.

Referring to FIG. 7, in the NR, a radio frame may be used for performinguplink and downlink transmission. A radio frame has a length of 10ms andmay be defined to be configured of two half-frames (HFs). A half-framemay include five lms subframes (SFs). A subframe (SF) may be dividedinto one or more slots, and the number of slots within a subframe may bedetermined in accordance with subcarrier spacing (SCS). Each slot mayinclude 12 or 14 OFDM(A) symbols according to a cyclic prefix (CP).

In case of using a normal CP, each slot may include 14 symbols. In caseof using an extended CP, each slot may include 12 symbols. Herein, asymbol may include an OFDM symbol (or CP-OFDM symbol) and an SC-FDMAsymbol (or DFT-s-OFDM symbol).

Table 1 shown below represents an example of a number of symbols perslot (N^(slot) _(symb)), a number slots per frame (N^(frame,u) _(slot)),and a number of slots per subframe (N^(subframe,u) _(slot)) inaccordance with an SCS configuration (u), in a case where a normal CP isused.

TABLE 1 SCS (15*2^(u)) N^(slot) _(symb) N^(frame, u) _(slot)N^(subframe, u) _(slot) 15 KHz (u = 0) 14 10 1 30 KHz (u = 1) 14 20 2 60KHz (u = 2) 14 40 4 120 KHz (u = 3) 14 80 8 240 KHz (u = 4) 14 160 16

Table 2 shows an example of a number of symbols per slot, a number ofslots per frame, and a number of slots per subframe in accordance withthe SCS, in a case where an extended CP is used.

TABLE 2 SCS (15*2^(u)) N^(slot) _(symb) N^(frame, u) _(slot)N^(subframe, u) _(slot) 60 KHz (u = 2) 12 40 4

In an NR system, OFDM(A) numerologies (e.g., SCS, CP length, and so on)between multiple cells being integrate to one UE may be differentlyconfigured. Accordingly, a (absolute time) duration (or section) of atime resource (e.g., subframe, slot or TTI) (collectively referred to asa time unit (TU) for simplicity) being configured of the same number ofsymbols may be differently configured in the integrated cells.

FIG. 8 shows a structure of a slot of an NR frame to which an exemplaryembodiment of the present disclosure can be applied.

Referring to FIG. 8, a slot includes a plurality of symbols in a timedomain. For example, in case of a normal CP, one slot may include 14symbols. However, in case of an extended CP, one slot may include 12symbols. Alternatively, in case of a normal CP, one slot may include 7symbols. However, in case of an extended CP, one slot may include 6symbols.

A carrier includes a plurality of subcarriers in a frequency domain. AResource Block (RB) may be defined as a plurality of consecutivesubcarriers (e.g., 12 subcarriers) in the frequency domain. A BandwidthPart (BWP) may be defined as a plurality of consecutive (P)RBs in thefrequency domain, and the BWP may correspond to one numerology (e.g.,SCS, CP length, and so on). A carrier may include a maximum of N numberBWPs (e.g., 5 BWPs). Data communication may be performed via anactivated BWP. Each element may be referred to as a Resource Element(RE) within a resource grid and one complex symbol may be mapped to eachelement.

Hereinafter, V2X or sidelink communication will be described in detail.

FIG. 9 shows a protocol stack for a sidelink communication to which theexemplary embodiment of the present disclosure can be applied. Morespecifically, (a) of FIG. 9 represents a user plane protocol stack ofLTE, and (b) of FIG. 9 represents a control plane protocol stack of LTE.

FIG. 10 shows a protocol stack for a sidelink communication to which theexemplary embodiment of the present disclosure can be applied. Morespecifically, (a) of FIG. 10 represents a user plane protocol stack ofNR, and (b) of FIG. 10 represents a control plane protocol stack of NR.

Hereinafter, Sidelink Synchronization Signal (SLSS) and synchronizationinformation will be described in detail.

SLSS is a sidelink specific sequence, which may include a PrimarySidelink Synchronization Signal (PSSS) and a Secondary SidelinkSynchronization Signal (SSSS). The PSSS may also be referred to as aSidelink Primary Synchronization Signal (S-PSS), and the SSSS may alsobe referred to as a Sidelink Secondary Synchronization Signal (S-SSS).

A Physical Sidelink Broadcast Channel (PSBCH) may be a (broadcast)channel through which basic (system) information that should first beknown by the user equipment (UE) before transmitting and receivingsidelink signals is transmitted. For example, the basic information maybe information related to SLSS, a Duplex mode (DM), TDD UL/DLconfiguration, information related to a resource pool, application typesrelated to SLSS, a subframe offset, broadcast information, and so on.

The S-PSS, the S-SSS, and the PSBCH may be included in a block format(e.g., a sidelink SS/PSBCH block, hereinafter referred to as S-SSB). TheS-SSB may have the same numerology (i.e., SCS and CP length) as aPhysical Sidelink Control Channel (PSCCH)/Physical Sidelink SharedChannel (PSSCH) within the carrier, and a transmission bandwidth mayexist within a (pre-)configured SL BWP. And, a frequency position of theS-SSB may be (pre-)configured. Therefore, the UE is not required toperform a hypothesis detection in order to discover the S-SSB in thecarrier.

Each SLSS may have a physical layer sidelink synchronization identity(ID), and the respective value may be equal to any one value rangingfrom 0 to 335. Depending upon any one of the above-described values thatis used, a synchronization source may also be identified. For example,values of 0, 168, 169 may indicate global navigation satellite systems(GNSS), values from 1 to 167 may indicate base stations, and values from170 to 335 may indicate that the source is outside of the coverage.Alternatively, among the physical layer sidelink synchronization IDvalues, values 0 to 167 may be values being used by a network, andvalues from 168 to 335 may be values being used outside of the networkcoverage.

FIG. 11 shows a UE performing V2X or sidelink communication to which anexemplary embodiment of the present disclosure can be applied.

Referring to FIG. 11, in V2X/sidelink communication, the term terminalmay mainly refer to a terminal (or equipment) used by a user. However,in case a network equipment, such as a base station, transmits andreceives signals in accordance with a communication scheme between thenetwork equipment and a user equipment (UE) (or terminal), the basestation may also be viewed as a type of user equipment (or terminal).

User equipment 1 (UE1) may select a resource unit corresponding to aspecific resource within a resource pool, which refers to a set ofresources, and UE1 may then be operated so as to transmit a sidelinksignal by using the corresponding resource unit. User equipment 2 (UE2),which is a receiving UE, may be configured with a resource pool to whichUE1 can transmit signals, and may then detect signals of UE1 from thecorresponding resource pool.

Herein, in case UE1 is within a connection range of the base station,the base station may notify the resource pool. Conversely, in case UE1is outside connection range of the base station, another UE may notifythe resource pool or a pre-determined resource may be used.

Generally, a resource pool may be configured in a plurality of resourceunits, and each UE may select one resource unit or a plurality ofresource units and may use the selected resource unit(s) for itssidelink signal transmission.

FIG. 12 shows an exemplary configuration of a resource unit to which anexemplary embodiment of the present disclosure can be applied.

Referring to FIG. 12, the total frequency resources of the resource poolmay be divided into N_(F) number of resource units, the total timeresources of the resource pool may be divided into N_(T) number ofresource units. Therefore, a total of N_(F)*N_(T) number of resourceunits may be defined in the resource pool. FIG. 12 shows an example of acase where the corresponding resource pool is repeated at a cycle of NTnumber of subframes.

As shown in FIG. 12, one resource unit (e.g., Unit #0) may beperiodically and repeatedly indicated. Alternatively, in order toachieve a diversity effect in the time or frequency level (ordimension), an index of a physical resource unit to which a logicalresource unit is mapped may be changed to a pre-determined pattern inaccordance with time. In such resource unit structure, the resource poolmay refer to a set of resource units that can be used for a transmissionthat is performed by a user equipment (UE), which intends to transmitsidelink signals.

The resource pool may be segmented to multiple types. For example,depending upon the content of a sidelink signal being transmitted fromeach resource pool, the resource pool may be divided as described below.

(1) Scheduling Assignment (SA) may be a signal including information,such as a position of a resource that is used for the transmission of asidelink data channel, a Modulation and Coding Scheme (MCS) or MIMOtransmission scheme needed for the modulation of other data channels, aTiming Advance (TA), and so on. The SA may also be multiplexed withsidelink data within the same resource unit and may then be transmitted,and, in this case, an SA resource pool may refer to a resource pool inwhich the SA is multiplexed with the sidelink data and then transmitted.The SA may also be referred to as a sidelink control channel.

(2) A Physical Sidelink Shared Channel (PSSCH) may be a resource poolthat is used by a transmitting UE for transmitting user data. If the SAis multiplexed with sidelink data within the same resource unit and thentransmitted, only a sidelink data channel excluding the SA informationmay be transmitted from the resource pool that is configured for thesidelink data channel. In other words, REs that were used fortransmitting SA information within a separate resource unit of the SAresource pool may still be used for transmitting sidelink data from theresource pool of a sidelink data channel.

(3) A discovery channel may be a resource pool that is used by thetransmitting UE for transmitting information, such as its own ID. Bydoing so, the transmitting UE may allow a neighboring UE to discover thetransmitting UE.

Even if the content of the above-described sidelink signal is the same,different resource pools may be used depending upon thetransmission/reception attribute of the sidelink signal. For example,even if the same sidelink data channel or discovery message is used, theresource pool may be identified as a different resource pool dependingupon a transmission timing decision method (e.g., whether thetransmission is performed at a reception point of the synchronizationreference signal or whether transmission is performed at the receptionpoint by applying a consistent timing advance), a resource allocationmethod (e.g., whether the base station designates a transmissionresource of a separate signal to a separate transmitting UE or whether aseparate transmitting UE selects a separate signal transmission resourceon its own from the resource pool), and a signal format (e.g., a numberof symbols occupied by each sidelink signal within a subframe or anumber of subframes being used for the transmission of one sidelinksignal) of the sidelink signal, signal intensity from the base station,a transmitting power intensity (or level) of a sidelink UE, and so on.

Hereinafter, resource allocation in a sidelink will be described indetail.

FIG. 13 shows user equipment (UE) operations according to a transmissionmode (TM) being related to sidelink/V2X communication to which anexemplary embodiment of the present disclosure can be applied.

(a) of FIG. 13 represents UE operations being related to transmissionmode 1 or transmission mode 3, and (b) of FIG. 13 represents UEoperations being related to transmission mode 2 or transmission mode 4.

Referring to (a) of FIG. 13, in transmission modes 1/3, the base stationperforms resource scheduling to UE1 via PDCCH (more specifically, DCI),and UE1 performs sidelink/V2X communication with UE2 according to thecorresponding resource scheduling. After transmitting sidelink controlinformation (SCI) to UE2 via physical sidelink control channel (PSCCH),UE1 may transmit data based on the SCI via physical sidelink sharedchannel (PSSCH). In case of an LTE sidelink, transmission mode 1 may beapplied to a general sidelink communication, and transmission mode 3 maybe applied to a V2X sidelink communication.

Referring to (b) of FIG. 13, in transmission modes 2/4, the UE mayschedule resources on its own. More specifically, in case of LTEsidelink, transmission mode 2 may be applied to a general sidelinkcommunication, and the UE may select a resource from a predeterminedresource pool on its own and may then perform sidelink operations.Transmission mode 4 may be applied to a V2X sidelink communication, andthe UE may carry out a sensing/SA decoding procedure, and so on, andselect a resource within a selection window on its own and may thenperform V2X sidelink operations. After transmitting the SCI to UE2 viaPSCCH, UE1 may transmit SCI-based data via PSSCH. Hereinafter, thetransmission mode may be abbreviated to mode.

In case of NR sidelink, at least two types of sidelink resourceallocation modes may be defined. In case of mode 1, the base station mayschedule sidelink resources that are to be used for sidelinktransmission. In case of mode 2, the user equipment (UE) may determine asidelink transmission resource from sidelink resources that areconfigured by the base station/network or predetermined sidelinkresources. The configured sidelink resources or the pre-determinedsidelink resources may be a resource pool. For example, in case of mode2, the UE may autonomously select a sidelink resource for transmission.For example, in case of mode 2, the UE may assist (or help) sidelinkresource selection of another UE. For example, in case of mode 2, the UEmay be configured with an NR configured grant for sidelink transmission.For example, in case of mode 2, the UE may schedule sidelinktransmission of another UE. And, mode 2 may at least support reservationof sidelink resources for blind retransmission.

Procedures related to sensing and resource (re-)selection may besupported in resource allocation mode 2. The sensing procedure may bedefined as a process decoding the SCI from another UE and/or sidelinkmeasurement. The decoding of the SCI in the sensing procedure may atleast provide information on a sidelink resource that is being indicatedby a UE transmitting the SCI. When the corresponding SCI is decoded, thesensing procedure may use L1 SL RSRP measurement, which is based on SLDMRS. The resource (re-)selection procedure may use a result of thesensing procedure in order to determine the resource for the sidelinktransmission.

Meanwhile, in the legacy V2X communication, traffic is mainly defined asperiodic traffic, and a message generation period or latency requirementof the traffic is set to be at least 100 ms. In addition, in case of theperiodic traffic, a size and the number of times of repetition of amessage for simulation is specified such that a fixed-sized message isperiodically transmitted 5 times in total, that is, 190 bytes aretransmitted 4 times and 300 bytes are transmitted one time. Therefore,in case of the mode 3 or 4 of LTE V2X communication, a base station or aUE selects (/reserves) or re-selects a resource with a period greaterthan or equal to 100 ms according to a period of a message to betransmitted. More specifically, in case of the mode 4 of LTE V2Xcommunication, a transmitting UE selects a transmission resource, basedon a sensing operation.

FIG. 14 shows an example of a resource selection method of a UEaccording to a mode 4 of LTE V2X communication to which an embodiment ofthe present disclosure is applicable.

Referring to FIG. 14, the UE may perform a sensing operation in thesensing window, exclude resources in which a resource collision isexpected in the selection window based on the result, and then randomlyselect a resource for V2X communication.

The sensing operation may perform an energy measurement operation for achannel and/or a predefined reference signal (RS) during a specificperiod (e.g., 1 second) before resource selection, and the UE mayrandomly select/(reserve) some of the candidate resourcesexpected/selected not to be used by other UEs based on the measuredvalue.

That is, the UE may perform a sensing operation in the sensing windowand select a resource based on the sensing operation in the selectionwindow. The sensing window and the selection window may mean apredetermined or preconfigured time and/or frequency resource.

For example, the UE may exclude some resources within the selectionwindow based on scheduling assignment (SA) decoding and/or otherconditions for the other UE. When the SA and data related thereto aretransmitted in the same subframe, measurement of a demodulationreference signal (DMRS) of a PSSCH may be supported.

The UE may exclude resources indicated or reserved by decoded SA andresources in which PSSCH Reference Signal Received Power (RSRP) in theassociated data resource is greater than or equal to a threshold.

The SA may include a ProSe per packet priority (PPPP) field, and thePPPP field may be configured with 3 bits. The PPPP field may carrypriority information of a packet.

The threshold may be set or preset as a function of priorityinformation. A value of the threshold may be changed in a range of [−128dBm] to [0 dBm] in 2 dB units (i.e., granularity of 2 dB) and thethreshold may further include positive infinity and negative infinity.

The threshold may be determined based on priority information of atransport block and priority information of the decoded SA, and 64values may be determined in advance.

The UE for decoding SA at TTI*m+c in a sensing period may assume thatthe same frequency resource by the SA is reserved at TTI*m+d+P*i. Here,P may be fixed to 100 and may be a settable value. i may be selectedwithin a range [0, 1, . . . , 10]. Selection of i may be a problem of UEimplementation. i may be signaled through a 4-bit field in the SA.

The UE may exclude X when a semi-static candidate resource X having aperiod P*I collides with a resource Y reserved by SA of another UE andsatisfies exclusion conditions through a threshold test.

When the number of the remaining resources after the process ofexcluding the resources as described above is less than 20% of the totalresources in the selection window, the UE increases a value of thethreshold (e.g., 3 dB), and then the resource exclusion process isperformed again and thus the number of remaining resources after theprocess of excluding the resources is greater than 20% of the totalresources in the selection window.

Thereafter, the UE may perform measurement with a period P for theremaining resources.

When the counter reaches a value of 0, the UE may maintain a currentresource with a probability p and reset the counter, or reselect theresource with a probability p-1. P is a carrier specific parameter, andmay be set/preset among [0, 0.2, 0.4, 0.6, 0.8].

The UE may measure/rank the remaining resources (e.g., PSSCH resources)based on total received energy and select some subset thereof. Forinstance, the subset may be a set of candidate resources having lowestreceived energy. For instance, a size of the subset may be 20% of totalresources in the selection window.

Thereafter, the UE may randomly select a resource in the subset.

When the UE transmits a transport block in a subframe, the UE may selectthe consecutive M number of subchannels.

However, the above-described sensing/resource selection operation may beeffective due to the characteristics of “periodicity” and “fixed size”of traffic in existing V2X communication. That is, because the UEsperiodically select (/reserve) resources, the transmitting UE couldpredict resources expected to be periodically selected by the other UEsthrough a sensing operation. That is, PSSCH-RSRP and S-RSSI valuesobserved (/measured) by the transmitting UE through a sensing operationduring the past specific section include periodicity of other UEs andthe transmitting UE in which, for example, a message generation period(or delay requirement) is 100 ms based on periodicity may select thebest resource based on sensing and use the selected resource untilresource reselection is triggered at a period of 100 ms. Therefore, thesensing operation at a system level is to minimize a collision withresources previously periodically occupied by other UEs by reflectingthe past resource occupancy state rather than a resource selection timepoint.

However, in services (e.g., vehicles platooning, information sharing forautomated driving, remote driving, etc.) considered in enhanced V2X(e.g., NR V2X or eV2X) communication, traffic of as little as four timesand as much as about twenty times, compared with an amount of existingtraffic may be generated. Further, the traffic may be aperiodic. In suchtraffic having aperiodic and variable sizes, existing sensing-basedresource selection may not be effective. In the case ofaperiodic/variable traffic, it is difficult to predict resourceallocation of other UEs and thus when a sensing-based resource selectionmethod is applied, the probability of collision occurrence betweenresources of other UEs and selection resources of a transmitting UEincreases.

Considering this aspect, hereinafter, in NR V2X communication or eV2Xcommunication, a method in which a UE selects a resource, based on adynamic threshold, and an apparatus supporting the method are proposedaccording to an embodiment of the present disclosure.

The transmitting UE (or AP) may use a carrier sense multiple access(CSMA) method belonging to a random access method among protocols foraccessing to a shared wireless channel. Here, the CSMA detects a channel(or carrier) before transmission in a principle of List before Talk(LBT), which reduces the possibility of collision with othertransmitting UEs.

More specifically, in the CSMA/collision avoidance (CA) method, thetransmitting UE observes a channel before transmitting data, anddetermines whether the channel is in an idle state based on ClearChannel Assessment (CCA), and if the channel is in an idle state, thetransmitting UE reduces the selected random counter and if the channelis in a busy state, the transmitting UE maintains the random counter.When the random counter becomes 0 by repeating such a process, thetransmitting UE transmits data and resets the random counter when NACKcomes (or ACK does not come) from the receiving UE after transmittingdata and thus performs the above process. In this case, in order tofurther prevent the collision, the transmitting UE may increaseexponentially a selection range of the random counter. That is, thetransmitting UE avoids a collision with a method of transmitting dataafter waiting for a time as long as the random counter by reducing therandom counter in the case of idle and by increasing the random counterin the case of busy.

CCA includes carrier sense (CCA-CS) and energy detection (CCA-ED). Whena receiver detects and decodes a preamble signal to detect anotherpreamble signal, the CCA-CS is a method of reporting the received frameto an upper layer in a busy state with a length as long as a lengthfield of a physical layer convergence protocol (PLCP) header indicates.

However, the CCA-ED determines that the channel is busy when themeasured RSSI value is larger than the threshold based on a fixedthreshold determined based on intensity of the current signals. TheCCA-CS determines whether the channel is in a busy status during anaccurate length interval, whereas the CCA-ED determines whether thechannel is in a busy status by comparing with a predefined threshold atevery slot time.

For example, in Wi-Fi, because interference does not come relativelyconsistently, the channel is occupied by determining whether the channelis in an idle/busy status based on a fixed threshold calculated usingonly current signal intensity (CCA-ED).

However, in the OFDM system like LTE, an influence of interferenceaccording to inter-symbol interference and co-channel interference isnot only large, but also in a congestion environment, interferencebetween the UEs and collisions of resource selection have a significantimpact on performance degradation and thus another resource allocationmethod is needed. For this reason, for example, in sidelink transmissionfor V2X in which the BS does not currently involve, resource allocationthrough sensing is performed.

In aperiodic/variable traffic, efficient resource allocation isavailable in a kind of “hybrid” method by appropriately using theresource allocation method based on the past situation like theaforementioned CCA method and sensing operation. That is, interferenceis considered by reflecting the past channel state, and dynamic resourceallocation is possible at every hour or shorter period for aperiodictraffic.

In frequent interference and irregular systems, past channel informationprior to resource selection is also required. Accordingly, there isproposed a method of dynamically selecting resources at every TTI or aspecific short duration based on a CCA threshold sequentiallydynamically changed by reflecting past channel information.

FIG. 15 shows a resource selection method of a UE according to anembodiment of the present disclosure.

Referring to FIG. 15, in step S1510, a UE may measure a resource duringa first time duration to determine a threshold (also referred to as aCCA threshold). In step S1520, the UE may determine a resource state ina second time duration, based on the threshold. In step S1530, the UEmay select a resource for V2X communication in the second time duration,based on the determination result.

Hereinafter, each step of FIG. 15 will be described in detail.

The present disclosure may be referred to as a kind of CCA-ED method,which requires a predefined CCA threshold.

According to an embodiment of the present disclosure, the threshold maybe determined dependent on priority information delivered with apredefined channel and/or a priority or latency requirement andreliability of the packet. Alternatively, the threshold may be afunction of a channel busy ratio (CBR). For example, when a traffic loadin coverage is high, a narrow target range is a general V2X attribute,and in this case, a relatively high interference resource may be used,and in contrast, when a traffic load is low, in order to satisfy a longtarget range, relatively low interference resources should be used. TheUE may determine information about the traffic load by measuring the CBRto use the information in order to determine the threshold.

Specifically, the threshold may be determined as follows.

(1) a value raised by a predefined specific dB based on an RSSI value tobe a boundary that satisfies a predefined specific ratio (e.g., lower x% or higher x %) or a boundary value thereof in a set of RSSIs measuredat every resource pool (or per resource unit, sub-channel, resourceelement, or full band) during a predefined specific period (e.g., 1second).

That is, a received signal strength indicator (RSSI) is measured in eachof candidate resources for the V2X communication during a first timeinterval, and a value corresponding to a lower x or upper x (here, x isa natural number) % among RSSI values measured for each of the candidateresources may be determined as the threshold.

Here, a resource to be a target of the RSSI set may be defined inadvance or may sequentially vary.

The channel monitoring process (e.g., RSSI measurement and RSSI setdetermination) may be always monitored regardless of resource selectiontriggering, and thus calculate the CCA threshold at any time based onthe past.

A ratio of x % may be defined in advance, and a corresponding value mayvary according to PPPP or a service type (e.g., application ID,destination ID). For example, a packet having high PPPP may lower avalue of x and thus a resource with less interference may be selected.For example, when an overall channel condition is good based on the CBR,a value of x may be increased to increase a selection width ofresources.

In the case of too much interference, in order to prevent an attempt ofresource selection, a threshold may have an upper limit or a lowerlimit.

(2) In order to satisfy a specific ratio (e.g., lower x % or higher x %)of the RSSI set defined in the above (1) according to predefinedreceiver sensitivity or modulation and coding rate sensitivity, thethreshold may be defined as a value increased by a specific dB (e.g., avalue greater by 20 dB than −82 dBm, which is the minimum sensitivityfor modulation and coding rate in a primary 20 MHz channel). In thisway, predefined receiver sensitivity may be dynamically adjusted by dBin which past channel conditions are reflected.

A process of obtaining a threshold in a situation where a resource poolis given as illustrated in FIG. 12 will be described in more detail.

It is assumed that the UE determines an idle/busy status of resources bymeasuring an RSSI of the past N_(T) number of time units in a situationin which a resource pool having a structure illustrated in FIG. 12 isgiven. Therefore, the UE has the total N_(T)*N_(F) number of resourcesin an RSSI measurement set using when determining an idle/busy status ofeach resource at a specific time point and measures an RSSI of eachresource. RSSIs measured in each of the N_(T)*NF number of resources maybe aligned, and then for example, a value to be a boundary of lower 20%may be determined as a threshold of IDLE/BUSY.

For example, when the UE determines whether the resource (or channel) isin an idle or busy status at a specific time t, it is assumed that itwas observed that an RSSI distribution of the resources measured duringthe past NT time is uniform distribution at [−100 dBm, −50 dBm] section.Accordingly, a threshold on whether a state of resources used by the UEat a time point t is idle/busy is −90 dBm, which is a boundary of lower20%.

As a time passes, when the UE again determines whether the resource (orchannel) is in an idle/busy status at a time point t+x, an overallsystem load is increased and thus it is assumed that it was observedthat an RSSI distribution of the resource measured during the past N_(T)time is a uniform distribution in [−80 dBm, 0 dBm] section. Therefore,in this case, a threshold on whether a resource is in an idle/busystatus is −64 dBm, which is a boundary of lower 20% on thisdistribution. Eventually, at a time point t+x, a system load isincreased and thus overall interference is increased, and in such asituation, the threshold is raised and thus even if some interferenceoccurs, an effect of attempting to use a relatively good resourceoccurs.

FIG. 16 shows a specific example of resource selection according to thepresent disclosure.

Referring to FIG. 16, the UE measures a first RSSI in a specificsection. Thereafter, the UE determines whether a resource (or channel)state is idle or busy using a threshold Th 1 determined by measurementof the first RSSI. If a distribution of the first RSSI measured duringthe specific interval is uniform in [−100 dBm, −50 dBm] section, thethreshold Th 1 may be, for example, −90 dBm, which is a boundary oflower 20% of the RSSI distribution.

After a certain time has elapsed, the UE measures a second RSSI in aspecific section. Thereafter, the UE determines whether a resource (orchannel) state is idle or busy using a threshold Th 2 determined bymeasurement of the second RSSI. For example, it is assumed that anoverall system load is increased and thus a distribution of the secondRSSI measurement result is uniform in [−80 dBm, 0 dBm] section.Therefore, in this case, the threshold Th 2 on whether the channel stateis idle/busy may be −64 dBm, which is a boundary of lower 20% in thedistribution.

Hereinafter, a description will be given on a method of selecting aresource based on the CCA-threshold defined above.

(1) The UE triggered by resource (re)selection may select randomly (orin random order) a resource (or resource unit, data pool, subchannel,RE, or full band) determined to an idle state in a current frame basedon the CCA threshold defined above. The randomly selected resource maybe reserved on the frequency/time axis as much as possible in the sizeof a packet to be transmitted, and the reserved information may benotified to other UEs through a predefined channel.

(2) The transmitting UE may select randomly (or in rank order) aresource (or resource unit, data pool, subchannel, RE, or full band)determined to an idle state in a current frame based on the CCAthreshold defined above and then reevaluate the resource for apredetermined time without using the resource.

The method of re-evaluation is, for example, a method of evaluating theselected resource at every TTI or at a specific short duration on thesame time axis, reducing a preselected random counter in case of idle,and using the resource, if a counter value is finally 0. When the caseof busy occurs while reducing the random counter, the existing randomcounter may be maintained and a new random counter may be defined. Inthis manner, collisions between UEs that simultaneously select the sameresource may be more prevented.

Here, the CCA threshold used in the random counter method may determinea CCA threshold based on observation up to that time point when resourceallocation is started by generation of a packet, until the correspondingpacket is transmitted (or until the counter is ended), the threshold maybe maintained, or the threshold may be updated at every TTI or at aspecific short duration while backing off.

A method of generating a random counter will be described. In acongestion situation, multiple UEs may attempt to preempt the sameresource, and this may cause performance degradation due to a collision.Therefore, counter generation may take into account a priority, latencyrequirement, and reliability of the CBR or a packet to be currentlysent. For example, if the CBR is high, a generation window of thecounter value may be increased, and a counter generation window may bereduced for a packet having a high priority.

A process of obtaining a more optimal CCA threshold than the abovemethod will be described.

In the above description, in order to reflect past channel conditions,idle/busy determination was made for all candidates of a currentresource selection time using CCA thresholds extracted from past RSSImonitoring sets. Implementation complexity is higher than that of theproposed method, but the following method may be used in a more optimalmethod.

FIG. 17 shows another example of extracting a threshold by the UEaccording to the present disclosure.

Referring to FIG. 17, in an RSSI sensing period, RSSI sensing may beperformed for each resource set separated with a frequency axis, anddifferent CCA thresholds may be extracted for each resource set.

That is, there is each resource set separated on the frequency axis(here, the unit of frequency may be various, such as 1 RE, 1RB, asubchannel, and a plurality of subchannels), and a value correspondingto the RSSI value of higher x % proposed above by each resource set maybe extracted as a CCA threshold at each frequency (e.g., 1 RE, 1 RB,subchannel, and a plurality of subchannels). Therefore, at a resourceselection triggering n time point, the UE may determine more optimallyan idle/bus status of the resource (or channel) with different CCAthresholds for each frequency.

As an effect when applying different CCA thresholds to the frequencyaxis, performance degradation according to a frequency selective channeloccurs in a V2X communication scenario with a large Doppler effect andidle/busy is determined with a CCA threshold in which frequencyselection is reflected and thus evaluation is more stably available.When it is difficult to extract the CCA threshold in all sensing periodswith high implementation complexity, a CCA threshold of each frequencymay be generated with the RSSI value periodically extracted in thesensing period.

It may be regarded that the above-proposed resource selection method hasadvantages over existing resource selection methods (e.g., sensing) whena UE generating aperiodic/variable traffic is dominant or commonlydistributed. Accordingly, the transmitting UE may select a resourceselection method from the existing method and the proposed methodaccording to the distribution of transmission traffic of the UEs in thecoverage. For example, when a UE for transmitting a periodic message inthe coverage is dominant, the existing resource selection method may beused, and in an opposite case, a proposed resource selection method maybe used. Use traffic distribution information of the UE may be signaledto the UE with a predefined channel or may be signaled directly to theUE through a higher layer signal. Further, as an example, the UE may usean existing operation when the packet to be simply transmitted isperiodic and use a proposed operation when the packet to be transmittedis aperiodic.

For example, in Wi-Fi, CCA is performed to occupy a full band, whereasthe above-proposed method has the advantage of being able to frequencydivision multiplexed with the frequency axis (e.g., monitoring for eachresource pool, each subchannel, and each resource element).

That is, in order to differentiate with CCA of Wi-Fi, the threshold testmay be applied to other frequencies at the same time point. For suchfrequency division multiplexing (FDM), time synchronization of each UEshould correspond and the same unit boundary should be maintained. Thereason why time synchronization should correspond is that FDM throughfast Fourier transform (FFT) is possible when a time boundary of each UEis the same. When FDM monitoring is supported, if a length of a timeunit is too long, much monitoring (or sensing) delay may occur. Whenthere are many delays to monitor with the frequency axis that do notsufficiently satisfy delay requirements, a length of a time interval fordetermining whether idle/busy should be fully short. Here, shortening ofa time length between units may mean that transmission TTIs are reducedtogether (e.g., 0.5 symbol TTIs) or may mean that only TTIs for CCA arereduced. However, when transmitting a packet, several consecutive unitsmay be used together.

The advantage of a method according to the present disclosure is acongested environment. When there is an “absolute” CCA threshold likeexisting Wi-Fi, there may be a large delay until actual transmissionafter resource selection triggering in a congested environment, but theproposed method determines a relatively good channel to an idle statewith the “relative” CCA threshold and thus there is no continuous delay.

Another advantage is that when transmitting delay-sensitive packets, ifa state of a channel is determined using a fixed threshold, for example,if the channel continuously has a value of a threshold or more due to afully low threshold, a problem may occur that the packet is dropped, butwhen a dynamic threshold is applied, it is difficult that such aphenomenon occurs. Further, in Wi-Fi, CCA was performed to occupy thefull band, but the proposed method has the advantage of being able tomonitor and occupy a channel by being frequency division multiplexedwith the frequency axis.

However, even if the dynamic threshold is used for resource selection ofthe UE as in the proposed method, a situation which is not good forresource selection of the UE may occur in a situation in which thetraffic load increases excessively or steeply. For example, although achannel condition was good (e.g., a CBR measurement value is low, thenumber of V2X vehicles located in a cell is small, a traffic load islow, etc.) in the past, the traffic load may increase at present sinceexcessive traffic occurs (e.g., traffic related to URLLC suddenlyoccurs). Alternatively, for example, although the channel situation wasgood in the past, the channel situation may become worse at present dueto a rapid increase in the number of V2X vehicles. For example, when theUE moves from a freeway environment to an urban environment, or when atraffic jam suddenly occurs due to a traffic accident or the like in thefreeway environment, the traffic load for the UE may increaseexcessively or steeply.

From a perspective of the UE, how the UE will recognize the environmentchanged as described above may be one issue. For example, the UE mayperiodically measure a channel (e.g., a CBR). In this case, based on achange amount between a previously measured CBR and a currently measuredCBR, the UE may determine whether the traffic load increases rapidly.For example, if the change amount of the CBR is greater than or equal toor exceeds a specific value, the UE may determine that the traffic loadincreases rapidly. Alternatively, for example, a base station maybroadcast cell-related channel environment information for each cellthrough system information to perform periodic or aperiodictransmission, or may signal intra-cell channel environment informationto a specific UE. In addition, when channel environment information foreach location is broadcast from the base station, the UE may determinewhether the traffic load increases rapidly through its own locationinformation.

Hereinafter, in the situation in which the traffic load increasesexcessively or steeply, a problem which may occur when the UEdynamically adjusts a threshold will be described in detail. Forexample, in an environment in which the traffic load is low, the UE maymeasure a channel state to determine a threshold, and the UE mayconfigure the threshold (e.g., a CCA threshold) to be small, based onthe measured channel state. However, the traffic load may increaserapidly at a timing at which the UE transmits data. As a result, theremay be a problem in that a resource satisfying the threshold hardlyexists, and the UE may not occupy a resource for transmission.

Further, in the situation in which the traffic load increases rapidly,there may also be a problem in that a latency requirement of a V2Xservice is not satisfied. For example, although the transmitting UEattempts to occupy a resource, based on the determined threshold (e.g.,the CCA threshold), a latency may occur in the resource occupancy of thetransmitting UE. Due to the latency, a situation may occur in which alatency budget of a packet to be transmitted by the transmitting UE isnot satisfied, and eventually, the transmitting UE may have to drop thepacket to be transmitted.

In order to solve the aforementioned problem, hereinafter, in NR V2Xcommunication or eV2X communication, a method in which a UE selects aresource, based on a dynamic threshold, and an apparatus supporting themethod are additionally proposed according to an embodiment of thepresent disclosure.

In order to solve the problem which occurs in the situation in which thetraffic load increases rapidly, hereinafter, a method of controlling aCCA threshold is proposed according to an embodiment of the presentdisclosure.

According to an embodiment of the present disclosure, a first CCAthreshold may be configured. In the present specification, the first CCAthreshold may also be referred to as a configured CCA threshold. Forexample, the first CCA threshold may be pre-defined for a UE.Alternatively, for example, a base station may configure the first CCAthreshold for the UE. Alternatively, for example, the base station maypre-configure the first CCA threshold for the UE. For example, the firstCCA threshold may be signaled to the UE through a pre-defined channel.The UE may compare a CCA threshold (e.g., a dynamic CCA threshold)determined through the embodiment of FIG. 15 to FIG. 17 with the firstCCA threshold (e.g., the configured CCA threshold). In addition, the UEmay determine/configure a greater value between the determined CCAthreshold and the configured threshold as the CCA threshold. Accordingto the proposed rule, for example, if current traffic increasesexcessively, the UE may replace the CCA threshold (i.e., the dynamic CCAthreshold) pre-determined to be low based on a history with a CCAthreshold having a greater value between the two values. Therefore, theUE may select a candidate group of an occupied resource, based on theconfigured CCA threshold, and there may be an increase in the candidategroup that can be selected by the UE.

According to an embodiment of the present disclosure, an availablethreshold range and a second CCA threshold may be configured. In thepresent specification, the second CCA threshold may also be referred toas an absolute CCA threshold. For example, the available threshold rangeand the second CCA threshold may be pre-defined for the UE.Alternatively, for example, the base station may configure the availablethreshold range and the second CCA threshold for the UE. Alternatively,for example, the base station may pre-configure the available thresholdrange and the second CCA threshold for the UE. For example, theavailable threshold range and the second CCA threshold may be signaledto the UE through a pre-defined channel. If the CCA threshold (i.e., thedynamic CCA threshold) determined through the embodiment of FIG. 15 toFIG. 17 is out of the available threshold range, the UE maydetermine/configure the second CCA threshold as the CCA threshold.

For example, it is assumed that the available threshold range is [−100dBm, −50 dBm], and the second CCA is −70 dBm. In this case, if the CCAthreshold (i.e., the dynamic CCA threshold) determined through theembodiment of FIG. 15 to FIG. 17 is −40 dBm, the dynamic CCA thresholdmay be out of the available threshold range. Therefore, the UE maydetermine/configure the second CCA as the CCA threshold. In addition,the UE may use the second CCA threshold to determine whether a channelis idle or busy. According to the proposed operation of the UE, even ifa traffic load increases suddenly, since the UE configures a range of athreshold, it is possible to avoid a problem in that the thresholdfluctuates excessively. However, according to the proposed operation ofthe UE, the method of determining the threshold of the UE, which isproposed according to the embodiment of FIG. 15 to FIG. 17, may not becompletely satisfied. For example, although the UE determines that acurrent channel state is good, based on a history, and thus determinesthat a threshold is low, since the determined threshold is out of theavailable threshold range, the UE may determine/configure the thresholdto a value higher than a threshold initially determined to be low. Toavoid such a phenomenon, the UE may determine the CCA threshold byconsidering channel measurement information (e.g., CBR, CSI, CQI, etc.).

Further, for example, as described above, due to a tradeoff relationshipbetween the dynamic CCA threshold and a load increase, a situation mayoccur in which a latency budget of a sidelink service is not satisfied.Therefore, according to an embodiment of the present disclosure, when itis near a latency limit of a packet to be currently transmitted by theUE, the UE may increase a value of the dynamic CCA threshold by aspecific dB to increase the number of available resources, or the UE mayoccupy a resource for transmitting the packet at a corresponding timingeven if there is a risk of a collision on the resource. For example,when a back-off time of a random counter is longer than a specificreference (or a specific time threshold), the UE may determine that itis near a latency limit of a packet to be currently transmitted.Alternatively, in order for the UE to occupy a resource, in a back-offprocess of the random counter, if the random counter is backed off in atime duration later than a specific timing according to a latencyrequirement (e.g., a specific 50% timing of the latency requirement),the UE may replace the dynamic CCA threshold with the second CCAthreshold in the time duration. According to the proposed method, evenif there is an increase in an influence of interference, there may be adecrease in a time delay required when the UE transmits a packet.Therefore, in the situation in which the traffic load increases rapidly,performance for the sidelink communication or V2X communication of theUE may be improved.

For example, the available threshold range, the second CCA threshold, orthe specific dB value may be pre-defined for each UE (e.g., in aUE-specific manner). For example, the available threshold range, thesecond CCA threshold, or the specific dB value may be pre-defined foreach cell (e.g., in a cell-specific manner). For example, the availablethreshold range, the second CCA threshold, or the specific dB value maybe pre-defined for each resource pool (e.g., in a resource pool-specificmanner). For example, a base station may configure the availablethreshold range, the second CCA threshold, or the specific dB value forthe UE through a pre-defined channel. For example, the base station maypre-configure the available threshold range, the second CCA threshold,or the specific dB value for the UE through the pre-defined channel.

According to the method proposed above, the UE attempts to occupy aresource as soon as possible in order to decrease a latency even ifthere is a risk of interference power on the resource to be occupied.However, such an operation of the UE may cause a rather wrong result inan environment in which a congestion is severe. For example, a pluralityof UEs may attempt to occupy the same resource having low interferencepower at the same timing. However, in this case, if the plurality of UEstransmit sidelink information through the same resource, a receiving UEmay fail to receive the sidelink information. In the presentspecification, the sidelink information may include sidelink data,sidelink control information, a sidelink-related packet, asidelink-related service, or the like. Therefore, there may be a need topropose a method of minimizing that the plurality of UEs occupy the sameresource at the same timing.

Hereinafter, according to an embodiment of the present disclosure, amethod of limiting resource occupancy of a transmitting UE and anapparatus supporting the method will be described.

FIG. 18 shows a procedure of limiting resource occupancy of atransmitting UE, according to an embodiment of the present disclosure.

Referring to FIG. 18, in step S1810, the transmitting UE may determine athreshold. For example, the threshold may be a CCA threshold (e.g., adynamic CCA threshold or a history-based CCA threshold) determinedthrough embodiments of FIG. 15 to FIG. 17. Alternatively, for example,the threshold may be a configured CCA threshold (e.g., the first CCAthreshold) or an absolute CCA threshold (i.e., the second CCAthreshold).

In step S1820, the transmitting UE may determine one or more occupiablesub-channels or one or more occupiable resources, based on thethreshold. For example, the transmitting UE may determine one or moresub-channels or one or more resources having a good channel state asoccupiable sub-channels or occupiable resources.

FIG. 19 is a drawing for explaining a problem which may occur when atransmitting UE selects a transmission resource from among occupiableresources.

Referring to FIG. 19, the transmitting UE may back off a random counterselected by the transmitting UE for an occupiable resource. That is, thetransmitting UE may decrease a value of the random counter selected bythe transmitting UE for the occupiable resource. However, for example,when a congestion is severe (e.g., when a CBR is higher than a specificvalue), the UE needs to avoid a time duration in which a plurality ofUEs may attempt to occupy a channel, such as a duration TIME2.Hereinafter, a problem which may occur when the UE does not avoid thetime duration in which the plurality of UEs may attempt to occupy thechannel in the environment where the congestion is severe will bedescribed in detail.

For example, in an embodiment of FIG. 19, it is assumed that thetransmitting UE obtains a random counter 6 in order to attempt to occupya resource in a packet arrival time TIME1 of a packet to be transmittedby the transmitting UE. Then, in the embodiment of FIG. 19, on asub-channel corresponding to TIME3 of a time axis and F5 of a frequencyaxis, the random counter will be zero. In this case, the UE may attemptto occupy a resource for which the random counter is zero. Further, theUE may randomly select a resource from among resources that can besub-occupied in a frequency axis at a timing at which the random counteris zero in order to avoid a resource occupancy collision with anotherUE. Since the operation in which the UE randomly selects the resource asdescribed above does not have effect on a time delay, it may be anoperation necessary to improve performance of the UE. However, theoperation of the UE which randomly selects the resource as describedabove may cause a collision of resource occupancy between a plurality ofUEs in a time duration in which the number of occupiable sub-channels issmall, such as TIME2, TIME4, or TIME6, which may lead to performancedeterioration of a system.

In order to avoid the aforementioned problem, in step S1830, thetransmitting UE may select a resource for transmitting sidelinkinformation, based on a ratio or the number of occupiable resourceswithin a specific time. Specifically, according to an embodiment of thepresent disclosure, the UE may not decrease the value of the randomcounter in the time duration in which the number of occupiablesub-channels is small. For example, the UE may exclude a time durationin which the number of occupiable sub-channels is small from theback-off time. For example, the time duration in which the number ofoccupiable sub-channels is small may be a time duration in which thenumber of occupiable sub-channels is less than a specific count N. Forexample, the time duration in which the number of occupiablesub-channels is small may be a time duration in which the number ofoccupiable sub-channels against the total sub-channels is less than aspecific ratio R. For example, the total number of sub-channels may bethe total number of sub-channels in a resource pool. For example, thetotal number of sub-channels may be the total number of sub-channels inthe entire frequency band.

For example, the specific count N or the specific ratio R may bepre-defined for the UE. Alternatively, for example, a base station mayconfigure the specific count N or the specific ratio R for the UE.Alternatively, for example, the base station may pre-configure thespecific count N or the specific ratio R for the UE. For example, thespecific count N or the specific ratio R may be a common configurationwhich is commonly used by all UEs in the resource pool. For example, thespecific count N or the specific ratio R may be a dedicatedconfiguration which is configured individually for each UE. In addition,for example, the specific count N or the specific ratio R may be relatedto an importance (e.g., a ProSe Per-Packet Priority (PPPP), a ProSePer-Packet Reliability (PPPR), or a latency requirement)) of a packet tobe transmitted. For example, the specific count N or the specific ratioR may be configured to different values according to the importance(e.g., the PPPP, the PPPR, or the latency requirement) of the packet tobe transmitted by the transmitting UE. For example, a specific count Nor specific ratio R related to a packet having a low PPPP (i.e., apacket having a high priority) may have a smaller value than a specificcount N or specific ratio R related to a packet having a high PPPP(i.e., a packet having a low priority).

FIG. 20 shows an example of selecting a transmission resource from amongresources that can be occupied by a transmitting UE, according to anembodiment of the present disclosure.

Referring to FIG. 20, it is assumed that the specific ratio R is 50%.Then, a time duration in which the UE decreases a value of a randomcounter may be TIME3 and TIME6. That is, the UE may not decrease thevalue of the random counter at TIME1, TIME2, TIME4, and TIME6. If it isassumed that the transmitting UE obtains a random counter 6 to attemptresource occupancy at a packet arrival time TIME1 of a packet to betransmitted by the transmitting UE, in an embodiment of FIG. 20, therandom count will be zero on a sub-channel corresponding to TIME6 of atime axis and F2 of a frequency axis. Therefore, in a time duration inwhich the number of occupiable sub-channels is small, such as TIME1,TIME2, TIME4, or TIME5, a collision may not occur for resource occupancybetween a plurality of UEs.

However, when all UEs perform the operation proposed in step S1830, morecollisions may occur for resource occupancy since all of the UEssimilarly attempt to occupy a resource on a time duration in which thereare many occupiable sub-channels. Therefore, it may not be necessary forall of the UEs to perform the operation proposed in step S1830. In orderto solve the aforementioned problem, the UE may determine whether toperform the operation proposed in step S1830 according to an importance(e.g., a PPPP, a PPPR, or a latency requirement) of a packet to betransmitted by the UE. Alternatively, the UE may differently apply thespecific count N or the specific ratio R according to the importance(e.g., the PPPP, the PPPR, or the latency requirement) of the packet tobe transmitted by the UE.

For example, when a service related to the packet to be transmitted bythe UE requires a low latency and a high reliability, the UE may notperform the operation proposed in step S1830 with respect to the packet.Therefore, a latency for the packet may be reduced. Alternatively, whenthe service related to the PPPP of the packet transmitted by the UErequires the low latency or the high reliability, the UE may configurethe specific count N or specific ratio R, which can be known through thePPPP or the packet, to be low. Therefore, the UE may attempt to back offa random counter in more time durations, and the latency for the packetmay be reduced.

FIG. 21 shows an example of selecting a transmission resource from amongresources that can be occupied by a plurality of transmitting UEs,according to an embodiment of the present disclosure.

Referring to FIG. 21, a back-off available timing may be differentaccording to an importance (e.g., a PPPP, a PPPR, or a latencyrequirement) of a packet to be transmitted by a UE. That is, a timeduration in which a value of a random counter can be decreased may bedifferent according to the importance (e.g., the PPPP, the PPPR, or thelatency requirement) of the packet to be transmitted by the UE. Forexample, in an embodiment of FIG. 21, if it is assumed that a specificcount N for a UE A is 5 and a specific count N for a UE B is 3, the UE Amay decrease the value of the random counter at TIME3 and TIME6, and theUE B may decrease the value of the random counter at TIME1, TIME3,TIME4, and TIME6. Through such an operation of the UE, a timing capableof decreasing the value of the random counter (i.e., a back-offdecreasing timing) may be adjusted according to the importance of thepacket to be transmitted. Further, a plurality of sub-channels that canbe occupied by a plurality of UEs in a specific time duration may beoccupied in a distributed manner.

Returning to FIG. 18, in step S1840, the transmitting UE may transmitsidelink information by using a selected resource.

A method in which a transmitting UE occupies a resource autonomously ina multi-channel CSMA manner in an NR V2X system is proposed above.However, the method is also applicable to not only the transmitting UEbut also a receiving UE. For example, various services may be supportedin NR V2X according to quality between links. For example, not onlysidelink communication for the purpose of providing a broadcast-basedsafety service but also sidelink communication for the purpose ofexchanging a unicast or groupcast-based specific service between linksmay be supported in the NR V2X. Herein, for example, in case of unicast,an operation for the setup of the unicast link may be required betweenspecific links. In addition, for the setup of the unicast link, thetransmitting UE and the receiving UE may exchange a plurality of piecesof information (e.g., a requested service, a requested quality ofservice (QoS), a sidelink capability, connection information, etc.). Inaddition, from a perspective of resource occupancy, a resource occupancysituation, a timing or location of an occupiable resource, aninterference level of a resource, or the like may be necessarily sharedbetween UEs. If the aforementioned information is not shared in theresource occupancy situation, a UE which performs the broadcast-basedV2X communication may attempt to occupy resources which collide witheach other. In addition, if the aforementioned information is not sharedin the resource occupancy situation, UEs which have perform the unicastor groupcast-based V2X communication may occupy a resource which cannotsatisfy a requested QoS level.

In order to share the information for resource occupancy between theUEs, not only the transmitting UE but also the receiving UE may requestfor information for link setup or resource allocation. In addition, thereceiving UE may use the multi-channel CSMA scheme to report anavailable resource and/or timing to a base station or neighboring UEs.More specifically, for example, the receiving UE may perform CCA with aCCA threshold derived through the proposed scheme in a current orspecific time window, and may report an available resource and/or timingto the base station or the neighboring UEs. In this process, the CCAthreshold may be updated every time or for each specific windowaccording to the proposed scheme. After performing the CCA based on thethreshold, the UE may notify information on a channel state measured ina resource of a specific timing. Alternatively, the UE may notifyinformation on a channel state measured in all resources within aspecific time window. When the UE configures information on an availableresource, the UE may indicate whether a corresponding resource (e.g., asub-channel) is available or unavailable through a bitmap (e.g., 0 or1). Alternatively, when the UE configures the information on theavailable resource, the UE may indicate this through an index of anavailable/unavailable sub-channel set.

In addition, in case of current Wi-Fi (i.e., IEEE 802.11), incommunication between an AP and a specific UE, a ready to send(RTS)/clear to send (CTS) may be signaled to avoid a channel occupancycollision with another UE. Also in unicast and/or groupcastcommunication of NR V2X, UEs may exchange information similar to theRTS/CRS signal based on the proposed multi-channel CSMA, and thus theUEs may more effectively share a channel. For example, when thetransmitting UE transmits a unicast request message or a groupcastrequest message, the receiving UE corresponding to the request messagemay feed back a CTS-related message. In this case, when the receiving UEconfigures the CTS-related message, the receiving UE may monitor aresource in advance as in the proposed scheme, and may allow informationon an available resource (e.g., a resource capable of satisfying QoS ofa unicast service) to be included in the CTS-related message.Accordingly, a resource capable of satisfying QoS of a service in acorresponding link may be occupied. In addition, according to animportance of the service, the receiving UE may allow informationindicating that a corresponding resource is used for a specific durationto be included in the CTS-related message, so that other UEs are notallowed to use a resource which is fed back through CTS after themonitoring. Through the aforementioned operation, other UEs which havereceived the CTS-related message may occupy other resources by avoidinga resource indicated by the CTS-related message. Accordingly, a resourcecollision can be avoided.

FIG. 22 shows a method of transmitting sidelink information by a firstapparatus 100 according to an embodiment of the present disclosure.

Referring to FIG. 22, in step S2210, the first apparatus 100 maydetermine a plurality of candidate resources, based on a threshold. Thethreshold may be determined or configured by various methods proposed inthe present specification. For example, additionally, the firstapparatus 100 may determine a first threshold, based on a channelmeasurement result, and may determine a greater value between the firstthreshold and a second threshold as the threshold. For example, thesecond threshold may be received from a base station. For example, thesecond threshold may be pre-defined for the first apparatus 100. Theplurality of candidate resources may be a resource of which a channelstate measured by the first apparatus 100 is greater than or equal to orexceeds the threshold.

In step S2220, the first apparatus 100 may select a resource fortransmitting the sidelink information in a specific time duration, fromamong the plurality of candidate resources. The resource may be selectedby various methods proposed in the present specification. The resourcefor transmitting the sidelink information may be a resource located on atime at which a value of a random counter selected by the firstapparatus 100 is zero. Additionally, the first apparatus 100 maydecrease the value of the random counter in the specific time duration.For example, the value of the random counter may not be decreased in atime duration other than the specific time duration.

The specific time duration may be a time duration in which the number ofcandidate resources that can be occupied by the first apparatus 100 isgreater than or equal to or exceeds a specific number. For example, thespecific number may be determined based on a priority of the sidelinkinformation. For example, the specific number may be determined to asmall value if the priority of the sidelink information is high.

The specific time duration may be a time duration in which a ratio ofthe number of candidate resources that can be occupied by the firstapparatus 100 against the total number of resources is greater than orequal to or exceeds a specific ratio. For example, the specific ratiomay be determined based on the priority of the sidelink information. Forexample, the specific ratio may be determined to a small value if thepriority of the sidelink information is high.

In step S2230, the first apparatus 100 may transmit the sidelinkinformation on the resource. The first apparatus 100 communicates withat least any one of autonomous vehicles other than a mobile UE, anetwork, or the first apparatus 100.

The proposed method may be performed by various devices described in thepresent specification. For example, a processor 102 of the firstapparatus 100 may determine a plurality of candidate resources, based ona threshold. In addition, the processor 102 of the first apparatus 100may select a resource for transmitting the sidelink information in aspecific time duration, from among the plurality of candidate resources.In addition, the processor 102 of the first apparatus 100 may control atransceiver 106 to transmit the sidelink information on the resource.

According to an embodiment of the present disclosure, in sidelinkcommunication or V2X communication, a UE can effectively occupy aresource.

Since the examples of the above-described proposed method may also beincluded as one of the implementation methods of the present disclosure,it will be apparent that the examples of the above-described proposedmethod can be considered as types of proposed methods. Additionally,although the above-described proposed methods may be independentlyimplemented (or embodied), the implementation may also be carried out ina combined (or integrated) form of part of the proposed methods. Herein,rules may be defined so that information on the application ornon-application of the proposed methods (or information on the rules ofthe proposed methods) can be notified to a UE, by a base station, or toa receiving UE, by a transmitting UE, through a predefined signal (e.g.,physical layer signal or high layer signal).

Hereinafter, an apparatus to which the present disclosure can be appliedwill be described.

The various descriptions, functions, procedures, proposals, methods,and/or operational flowcharts of the present disclosure described inthis document may be applied to, without being limited to, variousfields requiring wireless communication/connection (e.g., 5G) betweendevices.

Hereinafter, a description will be given in more detail with referenceto the drawings. In the following drawings/description, the samereference symbols may denote the same or corresponding hardware blocks,software blocks, or functional blocks unless described otherwise.

FIG. 23 shows a communication system (1) applied to the presentdisclosure.

Referring to FIG. 23, a communication system (1) applied to the presentdisclosure includes wireless devices, Base Stations (BSs), and anetwork. Herein, the wireless devices represent devices performingcommunication using Radio Access Technology (RAT) (e.g., 5G New RAT(NR)) or Long-Term Evolution (LTE)) and may be referred to ascommunication/radio/5G devices. The wireless devices may include,without being limited to, a robot (100 a), vehicles (100 b-1, 100 b-2),an eXtended Reality (XR) device (100 c), a hand-held device (100 d), ahome appliance (100 e), an Internet of Things (IoT) device (1000, and anArtificial Intelligence (AI) device/server (400). For example, thevehicles may include a vehicle having a wireless communication function,an autonomous driving vehicle, and a vehicle capable of performingcommunication between vehicles. Herein, the vehicles may include anUnmanned Aerial Vehicle (UAV) (e.g., a drone). The XR device may includean Augmented Reality (AR)/Virtual Reality (VR)/Mixed Reality (MR) deviceand may be implemented in the form of a Head-Mounted Device (HMD), aHead-Up Display (HUD) mounted in a vehicle, a television, a smartphone,a computer, a wearable device, a home appliance device, a digitalsignage, a vehicle, a robot, and so on. The hand-held device may includea smartphone, a smartpad, a wearable device (e.g., a smartwatch or asmartglasses), and a computer (e.g., a notebook). The home appliance mayinclude a TV, a refrigerator, and a washing machine. The IoT device mayinclude a sensor and a smartmeter. For example, the BSs and the networkmay be implemented as wireless devices and a specific wireless device(200 a) may operate as a BS/network node with respect to other wirelessdevices.

The wireless devices (100 a˜100 f) may be connected to the network (300)via the BSs (200). An AI technology may be applied to the wirelessdevices (100 a˜100 f) and the wireless devices (100 a˜100 f) may beconnected to the AI server (400) via the network (300). The network(300) may be configured using a 3G network, a 4G (e.g., LTE) network, ora 5G (e.g., NR) network. Although the wireless devices (100 a˜100 f) maycommunicate with each other through the BSs (200)/network (300), thewireless devices (100 a˜100 f) may perform direct communication (e.g.,sidelink communication) with each other without passing through theBSs/network. For example, the vehicles (100 b-1, 100 b-2) may performdirect communication (e.g., Vehicle-to-Vehicle(V2V)/Vehicle-to-everything (V2X) communication). The IoT device (e.g.,a sensor) may perform direct communication with other IoT devices (e.g.,sensors) or other wireless devices (100 a˜100 f).

Wireless communication/connections (150 a, 150 b) may be establishedbetween the wireless devices (100 a˜100 f)/BS (200), or BS(200)/wireless devices (100 a˜100 f). Herein, the wirelesscommunication/connections (150 a, 150 b) may be established throughvarious RATs (e.g., 5G NR) such as uplink/downlink communication (150a), sidelink communication (150 b) (or, D2D communication), or inter BScommunication (e.g., relay, Integrated Access Backhaul (IAB)). Thewireless devices and the BSs/the wireless devices may transmit/receiveradio signals to/from each other through the wirelesscommunication/connections (150 a, 150 b). For example, the wirelesscommunication/connections (150 a, 150 b) may transmit/receive signalsthrough various physical channels. To this end, at least a part ofvarious configuration information configuring processes, various signalprocessing processes (e.g., channel encoding/decoding,modulation/demodulation, and resource mapping/demapping), and resourceallocating processes, for transmitting/receiving radio signals, may beperformed based on the various proposals of the present disclosure.

FIG. 24 shows wireless devices applicable to the present disclosure.

Referring to FIG. 24, a first wireless device (100) and a secondwireless device (200) may transmit radio signals through various RATs(e.g., LTE and NR). Herein, {the first wireless device (100) and thesecond wireless device (200)} may correspond to {the wireless device(100 x) and the BS (200)} and/or {the wireless device (100 x) and thewireless device (100 x)} of FIG. 23.

The first wireless device (100) may include one or more processors (102)and one or more memories (104) and additionally further include one ormore transceivers (106) and/or one or more antennas (108). Theprocessor(s) (102) may control the memory(s) (104) and/or thetransceiver(s) (106) and may be configured to implement thedescriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed in this document. For example, theprocessor(s) (102) may process information within the memory(s) (104) togenerate first information/signals and then transmit radio signalsincluding the first information/signals through the transceiver(s)(106). The processor(s) (102) may receive radio signals including secondinformation/signals through the transceiver (106) and then storeinformation obtained by processing the second information/signals in thememory(s) (104). The memory(s) (104) may be connected to theprocessor(s) (102) and may store various information related tooperations of the processor(s) (102). For example, the memory(s) (104)may store software code including commands for performing a part or theentirety of processes controlled by the processor(s) (102) or forperforming the descriptions, functions, procedures, proposals, methods,and/or operational flowcharts disclosed in this document. Herein, theprocessor(s) (102) and the memory(s) (104) may be a part of acommunication modem/circuit/chip designed to implement RAT (e.g., LTE orNR). The transceiver(s) (106) may be connected to the processor(s) (102)and transmit and/or receive radio signals through one or more antennas(108). Each of the transceiver(s) (106) may include a transmitter and/ora receiver. The transceiver(s) (106) may be interchangeably used withRadio Frequency (RF) unit(s). In the present disclosure, the wirelessdevice may represent a communication modem/circuit/chip.

The second wireless device (200) may include one or more processors(202) and one or more memories (204) and additionally further includeone or more transceivers (206) and/or one or more antennas (208). Theprocessor(s) (202) may control the memory(s) (204) and/or thetransceiver(s) (206) and may be configured to implement thedescriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed in this document. For example, theprocessor(s) (202) may process information within the memory(s) (204) togenerate third information/signals and then transmit radio signalsincluding the third information/signals through the transceiver(s)(206). The processor(s) (202) may receive radio signals including fourthinformation/signals through the transceiver(s) (206) and then storeinformation obtained by processing the fourth information/signals in thememory(s) (204). The memory(s) (204) may be connected to theprocessor(s) (202) and may store various information related tooperations of the processor(s) (202). For example, the memory(s) (204)may store software code including commands for performing a part or theentirety of processes controlled by the processor(s) (202) or forperforming the descriptions, functions, procedures, proposals, methods,and/or operational flowcharts disclosed in this document. Herein, theprocessor(s) (202) and the memory(s) (204) may be a part of acommunication modem/circuit/chip designed to implement RAT (e.g., LTE orNR). The transceiver(s) (206) may be connected to the processor(s) (202)and transmit and/or receive radio signals through one or more antennas(208). Each of the transceiver(s) (206) may include a transmitter and/ora receiver. The transceiver(s) (206) may be interchangeably used with RFunit(s). In the present disclosure, the wireless device may represent acommunication modem/circuit/chip.

Hereinafter, hardware elements of the wireless devices (100, 200) willbe described more specifically. One or more protocol layers may beimplemented by, without being limited to, one or more processors (102,202). For example, the one or more processors (102, 202) may implementone or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP,RRC, and SDAP). The one or more processors (102, 202) may generate oneor more Protocol Data Units (PDUs) and/or one or more Service Data Units(SDUs) according to the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed in this document. Theone or more processors (102, 202) may generate messages, controlinformation, data, or information according to the descriptions,functions, procedures, proposals, methods, and/or operational flowchartsdisclosed in this document. The one or more processors (102, 202) maygenerate signals (e.g., baseband signals) including PDUs, SDUs,messages, control information, data, or information according to thedescriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed in this document and provide thegenerated signals to the one or more transceivers (106, 206). The one ormore processors (102, 202) may receive the signals (e.g., basebandsignals) from the one or more transceivers (106, 206) and obtain thePDUs, SDUs, messages, control information, data, or informationaccording to the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed in this document.

The one or more processors (102, 202) may be referred to as controllers,microcontrollers, microprocessors, or microcomputers. The one or moreprocessors (102, 202) may be implemented by hardware, firmware,software, or a combination thereof. As an example, one or moreApplication Specific Integrated Circuits (ASICs), one or more DigitalSignal Processors (DSPs), one or more Digital Signal Processing Devices(DSPDs), one or more Programmable Logic Devices (PLDs), or one or moreField Programmable Gate Arrays (FPGAs) may be included in the one ormore processors (102, 202). The descriptions, functions, procedures,proposals, methods, and/or operational flowcharts disclosed in thisdocument may be implemented using firmware or software and the firmwareor software may be configured to include the modules, procedures, orfunctions. Firmware or software configured to perform the descriptions,functions, procedures, proposals, methods, and/or operational flowchartsdisclosed in this document may be included in the one or more processors(102, 202) or stored in the one or more memories (104, 204) so as to bedriven by the one or more processors (102, 202). The descriptions,functions, procedures, proposals, methods, and/or operational flowchartsdisclosed in this document may be implemented using firmware or softwarein the form of code, commands, and/or a set of commands.

The one or more memories (104, 204) may be connected to the one or moreprocessors (102, 202) and store various types of data, signals,messages, information, programs, code, instructions, and/or commands.The one or more memories (104, 204) may be configured by Read-OnlyMemories (ROMs), Random Access Memories (RAMs), Electrically ErasableProgrammable Read-Only Memories (EPROMs), flash memories, hard drives,registers, cash memories, computer-readable storage media, and/orcombinations thereof. The one or more memories (104, 204) may be locatedat the interior and/or exterior of the one or more processors (102,202). The one or more memories (104, 204) may be connected to the one ormore processors (102, 202) through various technologies such as wired orwireless connection.

The one or more transceivers (106, 206) may transmit user data, controlinformation, and/or radio signals/channels, mentioned in the methodsand/or operational flowcharts of this document, to one or more otherdevices. The one or more transceivers (106, 206) may receive user data,control information, and/or radio signals/channels, mentioned in thedescriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed in this document, from one or moreother devices. For example, the one or more transceivers (106, 206) maybe connected to the one or more processors (102, 202) and transmit andreceive radio signals. For example, the one or more processors (102,202) may perform control so that the one or more transceivers (106, 206)may transmit user data, control information, or radio signals to one ormore other devices. The one or more processors (102, 202) may performcontrol so that the one or more transceivers (106, 206) may receive userdata, control information, or radio signals from one or more otherdevices. The one or more transceivers (106, 206) may be connected to theone or more antennas (108, 208) and the one or more transceivers (106,206) may be configured to transmit and receive user data, controlinformation, and/or radio signals/channels, mentioned in thedescriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed in this document, through the one ormore antennas (108, 208). In this document, the one or more antennas maybe a plurality of physical antennas or a plurality of logical antennas(e.g., antenna ports). The one or more transceivers (106, 206) mayconvert received radio signals/channels, and so on, from RF band signalsinto baseband signals in order to process received user data, controlinformation, radio signals/channels, and so on, using the one or moreprocessors (102, 202). The one or more transceivers (106, 206) mayconvert the user data, control information, radio signals/channels, andso on, processed using the one or more processors (102, 202) from thebase band signals into the RF band signals. To this end, the one or moretransceivers (106, 206) may include (analog) oscillators and/or filters.

FIG. 25 shows a signal process circuit for a transmission signal.

Referring to FIG. 25, a signal processing circuit (1000) may includescramblers (1010), modulators (1020), a layer mapper (1030), a precoder(1040), resource mappers (1050), and signal generators (1060). Anoperation/function of FIG. 25 may be performed, without being limitedto, the processors (102, 202) and/or the transceivers (106, 206) of FIG.24. Hardware elements of FIG. 25 may be implemented by the processors(102, 202) and/or the transceivers (106, 206) of FIG. 24. For example,blocks 1010˜1060 may be implemented by the processors (102, 202) of FIG.24. Alternatively, the blocks 1010 to 1050 may be implemented by theprocessors (102, 202) of FIG. 24 and the block 1060 may be implementedby the transceivers (106, 206) of FIG. 24.

Codewords may be converted into radio signals via the signal processingcircuit (1000) of FIG. 25. Herein, the codewords are encoded bitsequences of information blocks. The information blocks may includetransport blocks (e.g., a UL-SCH transport block, a DL-SCH transportblock). The radio signals may be transmitted through various physicalchannels (e.g., a PUSCH and a PDSCH).

Specifically, the codewords may be converted into scrambled bitsequences by the scramblers (1010). Scramble sequences used forscrambling may be generated based on an initialization value, and theinitialization value may include ID information of a wireless device.The scrambled bit sequences may be modulated to modulation symbolsequences by the modulators (1020). A modulation scheme may includepi/2-Binary Phase Shift Keying (pi/2-BPSK), m-Phase Shift Keying(m-PSK), and m-Quadrature Amplitude Modulation (m-QAM). Complexmodulation symbol sequences may be mapped to one or more transportlayers by the layer mapper (1030). Modulation symbols of each transportlayer may be mapped (precoded) to corresponding antenna port(s) by theprecoder (1040). Outputs z of the precoder (1040) may be obtained bymultiplying outputs y of the layer mapper (1030) by an N*M precodingmatrix W. Herein, N is the number of antenna ports and M is the numberof transport layers. The precoder (1040) may perform precoding afterperforming transform precoding (e.g., DFT) for complex modulationsymbols. Alternatively, the precoder (1040) may perform precodingwithout performing transform precoding.

The resource mappers (1050) may map modulation symbols of each antennaport to time-frequency resources. The time-frequency resources mayinclude a plurality of symbols (e.g., a CP-OFDMA symbols and DFT-s-OFDMAsymbols) in the time domain and a plurality of subcarriers in thefrequency domain. The signal generators (1060) may generate radiosignals from the mapped modulation symbols and the generated radiosignals may be transmitted to other devices through each antenna. Forthis purpose, the signal generators (1060) may include Inverse FastFourier Transform (IFFT) modules, Cyclic Prefix (CP) inserters,Digital-to-Analog Converters (DACs), and frequency up-converters.

Signal processing procedures for a signal received in the wirelessdevice may be configured in a reverse manner of the signal processingprocedures (1010˜1060) of FIG. 25. For example, the wireless devices(e.g., 100, 200 of FIG. 24) may receive radio signals from the exteriorthrough the antenna ports/transceivers. The received radio signals maybe converted into baseband signals through signal restorers. To thisend, the signal restorers may include frequency downlink converters,Analog-to-Digital Converters (ADCs), CP remover, and Fast FourierTransform (FFT) modules. Next, the baseband signals may be restored tocodewords through a resource demapping procedure, a postcodingprocedure, a demodulation processor, and a descrambling procedure. Thecodewords may be restored to original information blocks throughdecoding. Therefore, a signal processing circuit (not illustrated) for areception signal may include signal restorers, resource demappers, apostcoder, demodulators, descramblers, and decoders.

FIG. 26 shows another example of a wireless device applied to thepresent disclosure. The wireless device may be implemented in variousforms according to a use-case/service (refer to FIG. 23 and FIGS. 26 to31).

Referring to FIG. 26, wireless devices (100, 200) may correspond to thewireless devices (100, 200) of FIG. 24 and may be configured by variouselements, components, units/portions, and/or modules. For example, eachof the wireless devices (100, 200) may include a communication unit(110), a control unit (120), a memory unit (130), and additionalcomponents (140). The communication unit may include a communicationcircuit (112) and transceiver(s) (114). For example, the communicationcircuit (112) may include the one or more processors (102, 202) and/orthe one or more memories (104, 204) of FIG. 24. For example, thetransceiver(s) (114) may include the one or more transceivers (106, 206)and/or the one or more antennas (108, 208) of FIG. 24. The control unit(120) is electrically connected to the communication unit (110), thememory (130), and the additional components (140) and controls overalloperation of the wireless devices. For example, the control unit (120)may control an electric/mechanical operation of the wireless devicebased on programs/code/commands/information stored in the memory unit(130). The control unit (120) may transmit the information stored in thememory unit (130) to the exterior (e.g., other communication devices)via the communication unit (110) through a wireless/wired interface orstore, in the memory unit (130), information received through thewireless/wired interface from the exterior (e.g., other communicationdevices) via the communication unit (110).

The additional components (140) may be variously configured according totypes of wireless devices. For example, the additional components (140)may include at least one of a power unit/battery, input/output (I/O)unit, a driving unit, and a computing unit. The wireless device may beimplemented in the form of, without being limited to, the robot (100 aof FIG. 23), the vehicles (100 b-1, 100 b-2 of FIG. 23), the XR device(100 c of FIG. 23), the hand-held device (100 d of FIG. 23), the homeappliance (100 e of FIG. 23), the IoT device (100 f of FIG. 23), adigital broadcast terminal (or UE), a hologram device, a public safetydevice, an MTC device, a medicine device, a fintech device (or a financedevice), a security device, a climate/environment device, the AIserver/device (400 of FIG. 23), the BSs (200 of FIG. 23), a networknode, and so on. The wireless device may be used in a mobile or fixedplace according to a use-example/service.

In FIG. 26, the entirety of the various elements, components,units/portions, and/or modules in the wireless devices (100, 200) may beconnected to each other through a wired interface or at least a partthereof may be wirelessly connected through the communication unit(110). For example, in each of the wireless devices (100, 200), thecontrol unit (120) and the communication unit (110) may be connected bywire and the control unit (120) and first units (e.g., 130, 140) may bewirelessly connected through the communication unit (110). Each element,component, unit/portion, and/or module within the wireless devices (100,200) may further include one or more elements. For example, the controlunit (120) may be configured by a set of one or more processors. As anexample, the control unit (120) may be configured by a set of acommunication control processor, an application processor, an ElectronicControl Unit (ECU), a graphical processing unit, and a memory controlprocessor. As another example, the memory (130) may be configured by aRandom Access Memory (RAM), a Dynamic RAM (DRAM), a Read Only Memory(ROM)), a flash memory, a volatile memory, a non-volatile memory, and/ora combination thereof

Hereinafter, an example of implementing FIG. 26 will be described indetail with reference to the drawings.

FIG. 27 shows a hand-held device applied to the present disclosure. Thehand-held device may include a smartphone, a smartpad, a wearable device(e.g., a smartwatch or a smartglasses), or a portable computer (e.g., anotebook). The hand-held device may be referred to as a mobile station(MS), a user terminal (UT), a Mobile Subscriber Station (MSS), aSubscriber Station (SS), an Advanced Mobile Station (AMS), or a WirelessTerminal (WT).

Referring to FIG. 27, a hand-held device (100) may include an antennaunit (108), a communication unit (110), a control unit (120), a memoryunit (130), a power supply unit (140 a), an interface unit (140 b), andan I/O unit (140 c). The antenna unit (108) may be configured as a partof the communication unit (110). Blocks 110˜130/140 a˜140 c correspondto the blocks 110˜130/140 of FIG. 26, respectively.

The communication unit (110) may transmit and receive signals (e.g.,data and control signals) to and from other wireless devices or BSs. Thecontrol unit (120) may perform various operations by controllingconstituent elements of the hand-held device (100). The control unit(120) may include an Application Processor (AP). The memory unit (130)may store data/parameters/programs/code/commands needed to drive thehand-held device (100). The memory unit (130) may store input/outputdata/information. The power supply unit (140 a) may supply power to thehand-held device (100) and include a wired/wireless charging circuit, abattery, and so on. The interface unit (140 b) may support connection ofthe hand-held device (100) to other external devices. The interface unit(140 b) may include various ports (e.g., an audio I/O port and a videoI/O port) for connection with external devices. The I/O unit (140 c) mayinput or output video information/signals, audio information/signals,data, and/or information input by a user. The I/O unit (140 c) mayinclude a camera, a microphone, a user input unit, a display unit (140d), a speaker, and/or a haptic module.

As an example, in the case of data communication, the I/O unit (140 c)may obtain information/signals (e.g., touch, text, voice, images, orvideo) input by a user and the obtained information/signals may bestored in the memory unit (130). The communication unit (110) mayconvert the information/signals stored in the memory into radio signalsand transmit the converted radio signals to other wireless devicesdirectly or to a BS. The communication unit (110) may receive radiosignals from other wireless devices or the BS and then restore thereceived radio signals into original information/signals. The restoredinformation/signals may be stored in the memory unit (130) and may beoutput as various types (e.g., text, voice, images, video, or haptic)through the I/O unit (140 c).

FIG. 28 shows a vehicle or an autonomous driving vehicle applied to thepresent disclosure. The vehicle or autonomous driving vehicle may beimplemented by a mobile robot, a car, a train, a manned/unmanned AerialVehicle (AV), a ship, and so on.

Referring to FIG. 28, a vehicle or autonomous driving vehicle (100) mayinclude an antenna unit (108), a communication unit (110), a controlunit (120), a driving unit (140 a), a power supply unit (140 b), asensor unit (140 c), and an autonomous driving unit (140 d). The antennaunit (108) may be configured as a part of the communication unit (110).The blocks 110/130/140 a˜140 d correspond to the blocks 110/130/140 ofFIG. 26, respectively.

The communication unit (110) may transmit and receive signals (e.g.,data and control signals) to and from external devices such as othervehicles, BSs (e.g., gNBs and road side units), and servers. The controlunit (120) may perform various operations by controlling elements of thevehicle or the autonomous driving vehicle (100). The control unit (120)may include an Electronic Control Unit (ECU). The driving unit (140 a)may cause the vehicle or the autonomous driving vehicle (100) to driveon a road. The driving unit (140 a) may include an engine, a motor, apowertrain, a wheel, a brake, a steering device, and so on. The powersupply unit (140 b) may supply power to the vehicle or the autonomousdriving vehicle (100) and include a wired/wireless charging circuit, abattery, and so on. The sensor unit (140 c) may obtain a vehicle state,ambient environment information, user information, and so on. The sensorunit (140 c) may include an Inertial Measurement Unit (IMU) sensor, acollision sensor, a wheel sensor, a speed sensor, a slope sensor, aweight sensor, a heading sensor, a position module, a vehicleforward/backward sensor, a battery sensor, a fuel sensor, a tire sensor,a steering sensor, a temperature sensor, a humidity sensor, anultrasonic sensor, an illumination sensor, a pedal position sensor, andso on. The autonomous driving unit (140 d) may implement technology formaintaining a lane on which a vehicle is driving, technology forautomatically adjusting speed, such as adaptive cruise control,technology for autonomously driving along a determined path, technologyfor driving by automatically setting a path if a destination is set, andthe like.

For example, the communication unit (110) may receive map data, trafficinformation data, and so on, from an external server. The autonomousdriving unit (140 d) may generate an autonomous driving path and adriving plan from the obtained data. The control unit (120) may controlthe driving unit (140 a) such that the vehicle or the autonomous drivingvehicle (100) may move along the autonomous driving path according tothe driving plan (e.g., speed/direction control). In the middle ofautonomous driving, the communication unit (110) mayaperiodically/periodically obtain recent traffic information data fromthe external server and obtain surrounding traffic information data fromneighboring vehicles. In the middle of autonomous driving, the sensorunit (140 c) may obtain a vehicle state and/or surrounding environmentinformation. The autonomous driving unit (140 d) may update theautonomous driving path and the driving plan based on the newly obtaineddata/information. The communication unit (110) may transfer informationon a vehicle position, the autonomous driving path, and/or the drivingplan to the external server. The external server may predict trafficinformation data using AI technology, and so on, based on theinformation collected from vehicles or autonomous driving vehicles andprovide the predicted traffic information data to the vehicles or theautonomous driving vehicles.

FIG. 29 shows a vehicle applied to the present disclosure. The vehiclemay be implemented as a transport means, an aerial vehicle, a ship, andso on.

Referring to FIG. 29, a vehicle (100) may include a communication unit(110), a control unit (120), a memory unit (130), an I/O unit (140 a),and a positioning unit (140 b). Herein, the blocks 110 to 130/140 a˜140b correspond to blocks 110 to 130/140 of FIG. 26.

The communication unit (110) may transmit and receive signals (e.g.,data and control signals) to and from external devices such as othervehicles or BSs. The control unit (120) may perform various operationsby controlling constituent elements of the vehicle (100). The memoryunit (130) may store data/parameters/programs/code/commands forsupporting various functions of the vehicle (100). The I/O unit (140 a)may output an AR/VR object based on information within the memory unit(130). The I/O unit (140 a) may include a HUD. The positioning unit (140b) may obtain information on the position of the vehicle (100). Theposition information may include information on an absolute position ofthe vehicle (100), information on the position of the vehicle (100)within a traveling lane, acceleration information, and information onthe position of the vehicle (100) from a neighboring vehicle. Thepositioning unit (140 b) may include a GPS and various sensors.

As an example, the communication unit (110) of the vehicle (100) mayreceive map information and traffic information from an external serverand store the received information in the memory unit (130). Thepositioning unit (140 b) may obtain the vehicle position informationthrough the GPS and various sensors and store the obtained informationin the memory unit (130). The control unit (120) may generate a virtualobject based on the map information, traffic information, and vehicleposition information and the I/O unit (140 a) may display the generatedvirtual object in a window in the vehicle (1410, 1420). The control unit(120) may determine whether the vehicle (100) normally drives within atraveling lane, based on the vehicle position information. If thevehicle (100) abnormally exits from the traveling lane, the control unit(120) may display a warning on the window in the vehicle through the I/Ounit (140 a). In addition, the control unit (120) may broadcast awarning message regarding driving abnormity to neighboring vehiclesthrough the communication unit (110). According to situation, thecontrol unit (120) may transmit the vehicle position information and theinformation on driving/vehicle abnormality to related organizations.

FIG. 30 shows an XR device applied to the present disclosure. The XRdevice may be implemented by an HMD, a HUD mounted in a vehicle, atelevision, a smartphone, a computer, a wearable device, a homeappliance, a digital signage, a vehicle, a robot, and so on.

Referring to FIG. 30, an XR device (100 a) may include a communicationunit (110), a control unit (120), a memory unit (130), an I/O unit (140a), a sensor unit (140 b), and a power supply unit (140 c). Herein, theblocks 110 to 130/140 a˜140 c correspond to the blocks 110 to 130/140 ofFIG. 26, respectively.

The communication unit (110) may transmit and receive signals (e.g.,media data and control signals) to and from external devices such asother wireless devices, hand-held devices, or media servers. The mediadata may include video, images, and sound. The control unit (120) mayperform various operations by controlling constituent elements of the XRdevice (100 a). For example, the control unit (120) may be configured tocontrol and/or perform procedures such as video/image acquisition,(video/image) encoding, and metadata generation and processing. Thememory unit (130) may store data/parameters/programs/code/commandsneeded to drive the XR device (100 a)/generate XR object. The I/O unit(140 a) may obtain control information and data from the exterior andoutput the generated XR object. The I/O unit (140 a) may include acamera, a microphone, a user input unit, a display unit, a speaker,and/or a haptic module. The sensor unit (140 b) may obtain an XR devicestate, surrounding environment information, user information, and so on.The sensor unit (140 b) may include a proximity sensor, an illuminationsensor, an acceleration sensor, a magnetic sensor, a gyro sensor, aninertial sensor, an RGB sensor, an IR sensor, a fingerprint recognitionsensor, an ultrasonic sensor, a light sensor, a microphone and/or aradar. The power supply unit (140 c) may supply power to the XR device(100 a) and include a wired/wireless charging circuit, a battery, and soon.

For example, the memory unit (130) of the XR device (100 a) may includeinformation (e.g., data) needed to generate the XR object (e.g., anAR/VR/MR object). The I/O unit (140 a) may receive a command formanipulating the XR device (100 a) from a user and the control unit(120) may drive the XR device (100 a) according to a driving command ofa user. For example, when a user desires to watch a film or news throughthe XR device (100 a), the control unit (120) transmits content requestinformation to another device (e.g., a hand-held device (100 b)) or amedia server through the communication unit (130). The communicationunit (130) may download/stream content such as films or news fromanother device (e.g., the hand-held device (100 b)) or the media serverto the memory unit (130). The control unit (120) may control and/orperform procedures such as video/image acquisition, (video/image)encoding, and metadata generation/processing with respect to the contentand generate/output the XR object based on information on a surroundingspace or a real object obtained through the I/O unit (140 a)/sensor unit(140 b).

The XR device (100 a) may be wirelessly connected to the hand-helddevice (100 b) through the communication unit (110) and the operation ofthe XR device (100 a) may be controlled by the hand-held device (100 b).For example, the hand-held device (100 b) may operate as a controller ofthe XR device (100 a). To this end, the XR device (100 a) may obtaininformation on a 3D position of the hand-held device (100 b) andgenerate and output an XR object corresponding to the hand-held device(100 b).

FIG. 31 shows a robot applied to the present disclosure. The robot maybe categorized into an industrial robot, a medical robot, a householdrobot, a military robot, and so on, according to a used purpose orfield.

Referring to FIG. 31, a robot (100) may include a communication unit(110), a control unit (120), a memory unit (130), an I/O unit (140 a), asensor unit (140 b), and a driving unit (140 c). Herein, the blocks 110to 130/140 a-140 c correspond to the blocks 110 to 130/140 of FIG. 26,respectively.

The communication unit (110) may transmit and receive signals (e.g.,driving information and control signals) to and from external devicessuch as other wireless devices, other robots, or control servers. Thecontrol unit (120) may perform various operations by controllingconstituent elements of the robot (100). The memory unit (130) may storedata/parameters/programs/code/commands for supporting various functionsof the robot (100). The I/O unit (140 a) may obtain information from theexterior of the robot (100) and output information to the exterior ofthe robot (100). The I/O unit (140 a) may include a camera, amicrophone, a user input unit, a display unit, a speaker, and/or ahaptic module. The sensor unit (140 b) may obtain internal informationof the robot (100), surrounding environment information, userinformation, and so on. The sensor unit (140 b) may include a proximitysensor, an illumination sensor, an acceleration sensor, a magneticsensor, a gyro sensor, an inertial sensor, an IR sensor, a fingerprintrecognition sensor, an ultrasonic sensor, a light sensor, a microphone,a radar, and so on. The driving unit (140 c) may perform variousphysical operations such as movement of robot joints. In addition, thedriving unit (140 c) may cause the robot (100) to travel on the road orto fly. The driving unit (140 c) may include an actuator, a motor, awheel, a brake, a propeller, and so on.

FIG. 32 shows an AI device applied to the present disclosure. The AIdevice may be implemented by a fixed device or a mobile device, such asa TV, a projector, a smartphone, a PC, a notebook, a digital broadcastterminal (or UE), a tablet PC, a wearable device, a Set Top Box (STB), aradio, a washing machine, a refrigerator, a digital signage, a robot, avehicle, and so on.

Referring to FIG. 32, an AI device (100) may include a communicationunit (110), a control unit (120), a memory unit (130), an I/O unit (140a/140 b), a learning processor unit (140 c), and a sensor unit (140 d).The blocks 110 to 130/140 a˜140 d correspond to blocks 110 to 130/140 ofFIG. 26, respectively.

The communication unit (110) may transmit and receive wired/radiosignals (e.g., sensor information, user input, learning models, orcontrol signals) to and from external devices such as other AI devices(e.g., 100 x, 200, 400 of FIG. 23) or an AI server (200) usingwired/wireless communication technology. To this end, the communicationunit (110) may transmit information within the memory unit (130) to anexternal device and transmit a signal received from the external deviceto the memory unit (130).

The control unit (120) may determine at least one feasible operation ofthe AI device (100), based on information which is determined orgenerated using a data analysis algorithm or a machine learningalgorithm. The control unit (120) may perform an operation determined bycontrolling constituent elements of the AI device (100). For example,the control unit (120) may request, search, receive, or use data of thelearning processor unit (140 c) or the memory unit (130) and control theconstituent elements of the AI device (100) to perform a predictedoperation or an operation determined to be preferred among at least onefeasible operation. The control unit (120) may collect historyinformation including the operation contents of the AI device (100) andoperation feedback by a user and store the collected information in thememory unit (130) or the learning processor unit (140 c) or transmit thecollected information to an external device such as an AI server (400 ofFIG. 23). The collected history information may be used to update alearning model.

The memory unit (130) may store data for supporting various functions ofthe AI device (100). For example, the memory unit (130) may store dataobtained from the input unit (140 a), data obtained from thecommunication unit (110), output data of the learning processor unit(140 c), and data obtained from the sensor unit (140). The memory unit(130) may store control information and/or software code needed tooperate/drive the control unit (120).

The input unit (140 a) may obtain various types of data from theexterior of the AI device (100). For example, the input unit (140 a) mayobtain learning data for model learning, and input data to which thelearning model is to be applied. The input unit (140 a) may include acamera, a microphone, and/or a user input unit. The output unit (140 b)may generate output related to a visual, auditory, or tactile sense. Theoutput unit (140 b) may include a display unit, a speaker, and/or ahaptic module. The sensing unit (140) may obtain at least one ofinternal information of the AI device (100), surrounding environmentinformation of the AI device (100), and user information, using varioussensors. The sensor unit (140) may include a proximity sensor, anillumination sensor, an acceleration sensor, a magnetic sensor, a gyrosensor, an inertial sensor, an RGB sensor, an IR sensor, a fingerprintrecognition sensor, an ultrasonic sensor, a light sensor, a microphone,and/or a radar.

The learning processor unit (140 c) may learn a model consisting ofartificial neural networks, using learning data. The learning processorunit (140 c) may perform AI processing together with the learningprocessor unit of the AI server (400 of FIG. 23). The learning processorunit (140 c) may process information received from an external devicethrough the communication unit (110) and/or information stored in thememory unit (130). In addition, an output value of the learningprocessor unit (140 c) may be transmitted to the external device throughthe communication unit (110) and may be stored in the memory unit (130).

1-15. (canceled)
 16. A method for performing, by a first apparatus,wireless communication, the method comprising: receiving a request forinformation related to at least one candidate resource from a secondapparatus; obtaining a plurality of channel state values, based onchannel measurement for a plurality of first resources in a first timeinterval; determining the at least one candidate resource, based on theplurality of channel state values and a first threshold; andtransmitting the information related to the at least one candidateresource to the second apparatus, based on the request, wherein at leastone channel state value related to the at least one candidate resourceis less than or equal to the first threshold.
 17. The method of claim16, further comprising: determining a second threshold based on channelmeasurement for a plurality of second resources in a second timeinterval, wherein a third threshold is configured for the firstapparatus.
 18. The method of claim 17, wherein the first threshold is alarger value among the second threshold and the third threshold.
 19. Themethod of claim 17, wherein based on the second threshold outsidethreshold range, the first threshold is the third threshold, and whereinbased on the second threshold within the threshold range, the firstthreshold is the second threshold.
 20. The method of claim 17, whereinbased on a ratio of a remaining delay budget to a delay budget of apacket to be transmitted by the first apparatus which is less than acertain ratio, the first threshold is a value obtained by adding anoffset value to the second threshold or the third threshold.
 21. Themethod of claim 17, wherein based on a ratio of a remaining delay budgetto a delay budget of a packet to be transmitted by the first apparatuswhich is less than a certain ratio, the first threshold is the thirdthreshold.
 22. The method of claim 16, further comprising: selecting aresource for sidelink (SL) transmission from among the at least onecandidate resource in a third time interval; and performing the SLtransmission based on the resource.
 23. The method of claim 22, furthercomprising: selecting a random counter value; and decreasing the randomcounter value in the third time interval, wherein the random countervalue is not decreased in a time period other than the third timeperiod.
 24. The method of claim 23, wherein the resource is a resourcelocated on a time when the random counter value is zero within the thirdtime interval.
 25. The method of claim 23, wherein the third timeinterval is a time interval in which a number of the at least onecandidate resource is greater than or equal to a specific number or aspecific ratio.
 26. The method of claim 25, wherein the specific numberor the specific ratio is determined based on a priority related to theSL transmission.
 27. The method of claim 26, wherein the higher thepriority related to the SL transmission, the smaller the specific numberor the specific ratio is determined.
 28. The method of claim 16, whereinthe information related to the at least one candidate resource includesinformation related to a resource available by the first apparatus orinformation related to a resource unavailable by the first apparatus.29. A first apparatus for performing wireless communication, the firstapparatus comprising: one or more memories storing instructions; one ormore transceivers; and one or more processors connected to the one ormore memories and the one or more transceivers, wherein the one or moreprocessors execute the instructions to: receive a request forinformation related to at least one candidate resource from a secondapparatus; obtain a plurality of channel state values, based on channelmeasurement for a plurality of first resources in a first time interval;determine the at least one candidate resource, based on the plurality ofchannel state values and a first threshold; and transmit the informationrelated to the at least one candidate resource to the second apparatus,based on the request, wherein at least one channel state value relatedto the at least one candidate resource is less than or equal to thefirst threshold.
 30. An apparatus configured to control a first userequipment (UE), the apparatus comprising: one or more processors; andone or more memories connected to the one or more processors and storinginstructions, wherein the one or more processors execute theinstructions to: receive a request for information related to at leastone candidate resource from a second UE; obtain a plurality of channelstate values, based on channel measurement for a plurality of firstresources in a first time interval; determine the at least one candidateresource, based on the plurality of channel state values and a firstthreshold; and transmit the information related to the at least onecandidate resource to the second UE, based on the request, wherein atleast one channel state value related to the at least one candidateresource is less than or equal to the first threshold.